Ezell's Javascript

Front 1

Name all the javascript string functions

Back 1

1. charAt
2. charCodeAt
3. concat
4. fromCharCode
5. indexOf
6. lastIndexOf
7. match
8. replace
9. search
10. slice
11. split
12. substr
13. substring
14. toLowerCase
15. toUpperCase

Front 2

charAt()

Back 2

Returns the character at the "x" position within the string.

Front 3

charCodeAt(x)

Back 3

Returns the Unicode value of the character at position "x" within the string.

Front 4

concat(v1, v2,...)

Back 4

Combines one or more strings (arguments v1, v2 etc) into the existing one and returns the combined string. Original string is not modified.

Front 5

fromCharCode(c1, c2,...)

Back 5

Returns a string created by using the specified sequence of Unicode values (arguments c1, c2 etc). Method of String object, not String instance. For example: String.fromCharCode().

Front 6

indexOf(substr, [start])

Back 6

Searches and (if found) returns the index number of the searched character or substring within the string. If not found, -1 is returned. "Start" is an optional argument specifying the position within string to begin the search. Default is 0.

Front 7

lastIndexOf(substr, [start])

Back 7

Searches and (if found) returns the index number of the searched character or substring within the string. Searches the string from end to beginning. If not found, -1 is returned. "Start" is an optional argument specifying the position within string to begin the search. Default is string.length-1.

Front 8

match(regexp)

Back 8

Executes a search for a match within a string based on a regular expression. It returns an array of information or null if no match is found.

Front 9

replace( regexp, replacetext)

Back 9

Searches and replaces the regular expression portion (match) with the replaced text instead.

Front 10

search(regexp)

Back 10

Tests for a match in a string. It returns the index of the match, or -1 if not found.

Front 11

slice(start, [end])

Back 11

Returns a substring of the string based on the "start" and "end" index arguments, NOT including the "end" index itself. "End" is optional, and if none is specified, the slice includes all characters from "start" to end of string.

Front 12

split(delimiter, [limit])

Back 12

Splits a string into many according to the specified delimiter, and returns an array containing each element. The optional "limit" is an integer that lets you specify the maximum number of elements to return.

Front 13

substr(start, [length])

Back 13

Returns the characters in a string beginning at "start" and through the specified number of characters, "length". "Length" is optional, and if omitted, up to the end of the string is assumed.

Front 14

substring(from, [to])

Back 14

Returns the characters in a string between "from" and "to" indexes, NOT including "to" inself. "To" is optional, and if omitted, up to the end of the string is assumed.

Front 15

toLowerCase()

Back 15

Returns the string with all of its characters converted to lowercase.

Front 16

toUpperCase()

Back 16

Returns the string with all of its characters converted to uppercase.

Front 17

valueOf

Back 17

Returns the primitive value of a String object

Front 18

How would you make a singleton in js

Back 18

var Singleton =(function(){
var instantiated;
function init (){
// all singleton code goes here
return {
publicWhatever:function(){
alert('whatever')
},
publicProperty:2
}
}

return {
getInstance :function(){
if (!instantiated){
instantiated = init();
}
return instantiated;
}
}
})()

//to call public methods now use:
Singleton.getInstance().publicWhatever();

Front 19

factory method in js

Back 19

factory = function(){
return{
name: "Ezell",
getName : function(){
return this.name;
}
}
}

Front 20

synchronus AJAX request in javascript using GET

Back 20

var xhr = new XMLHttpRequest();

xhr.open("GET", "textfile.txt", false);

xhr.send(null);

alert(xhr.responseText)

Front 21

Asynchronus request with get

Back 21

var xhr = new XMLHttpRequest();

xhr.open("GET", "textfile.txt", false);

xhr.onreadystatechange = function(){
if(xhr.readyState === 4){
if((xhr.status >= 200 && xhr.status < 300) && status === 304){
alert(xhr(responseText)
}else{
alert("something bad happened")
}
alert(xhr.responseText);
}
}
xhr.send(null);

Front 22

the difference between the constructor function and the factory method

Back 22

The difference between the constructor function and the factory method is the constructor makes an datatype and the factory only makes a object

Front 23

describe error handling in js

Back 23

try{
alert("this code will not fail");
abert("this code will fail");
alert("this code will not excute");
}catch{
alert("an error occured. This will run when something in the try block fails");
}finally{
alert("this will always run")
}

Front 24

How would use the xhr technology with the post request

Back 24

var xhr = new XMLHttpRequest();

xhr.open("POST", "textfile.txt", true);
var data = getRequestBody();
xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded")
xhr.onreadystatechange = function(){
if(xhr.readyState === 4){
if((xhr.status >= 200 && xhr.status < 300) && status === 304){
alert(xhr(responseText)
}else{
alert("something bad happened")
}
alert(xhr.responseText);
}
}

xhr.send(data);

var getRequestBody = function(){
var form = document.getElementById();
}

Front 25

primitive values in js

Back 25

String
Number
Boolean
Undefined
Null

Front 26

Reference types in js

Back 26

Object
Array
function
Date
RegExp

Front 27

how can you force garbage collector?

Back 27

make a primitive

Front 28

create a person object with object literal notation

Back 28

var Person{
firstName: "Ezell",
lastName : "Burke",
getWholeName : function(){
console.log("Hello my name is "+firstName+" "+lastName+".");
}
}

Front 29

What are the parameters to Object.define Property?

Back 29

1. the object the property beliongs to.
2. the name of the property string value
3. object called the descirptor object- defines the options we will set on the property
-data descriptors
-accessor descriptors

Front 30

describe Object.defineProperty

Back 30

This method allows precise addition to or modification of a property on an object.

Front 31

Property descriptors

Back 31

Property descriptors present in objects come in two main flavors: data descriptors and accessor descriptors.

Front 32

data descriptors

Back 32

A data descriptor is a property that has a value, which may or may not be writable.

Front 33

accessor descriptor

Back 33

An accessor descriptor is a property described by a getter-setter pair of functions.

Front 34

what keys do the property descriptors share?

Back 34

Both data and accessor descriptors are objects. They share the following optional keys:

1. configurable
true if and only if the type of this property descriptor may be changed and if the property may be deleted from the corresponding object. Defaults to false.
2. enumerable
true if and only if this property shows up during enumeration of the properties on the corresponding object. Defaults to false.

Front 35

What are the optional keys for data descriptors?

Back 35

A data descriptor also has the following optional keys:

1. value
The value associated with the property. Can be any valid JavaScript value (number, object, function, etc) Defaults to undefined.
2. writable
True if and only if the value associated with the property may be changed with an assignment operator. Defaults to false.

Front 36

What are the optional keys for accesor descriptor?

Back 36

An accessor descriptor also has the following optional keys:

1. get
A function which serves as a getter for the property, or undefined if there is no getter. The function return will be used as the value of property. Defaults to undefined.
2. set
A function which serves as a setter for the property, or undefined if there is no setter. The function will receive as only argument the new value being assigned to the property. Defaults to undefined.

Front 37

When should you use a constructor function?

Back 37

Use a constructor function when you need more than one of the same type of object otherwise use an object literal.

Front 38

Example of a constructor function.

Back 38

var Person = function(firstName, lastName){
this.firstName = firstName;
this.lastName = lastName;

Object.defineProperty(this, "fullName", {
get : function(){
return this.firstName + " " + this.lastName;
}
});

//define method in Prototype
Person.prototype.sayHi = function(){
return "Hi there."
}
}
var Person = new Person('Ezell', 'Burke');

Front 39

When should you use hasOwnProperty method

Back 39

Use the hasOwnProperty() method to differentiate between own properties and prototype properties.

Front 40

What should you do when you completly overwrite a prototype?

Back 40

You should reset the constructors of the prototypes:
Person.prototype.constructor = Person;

Front 41

javascript global functions

Back 41

1. decodeURI
2. decodeURiComponent
3. encodeURI
4. escape
5. eval
6. isFinite
7. isNaN
8. Number
9. parseFloat
10. parseInt
11. String
12. unescape

Front 42

encodeURI()

Back 42

This function encodes special characters, except: , / ? : @ & = + $ # (Use encodeURIComponent() to encode these characters).

Front 43

encodeURIComponent()

Back 43

The encodeURIComponent() function encodes a URI component.

Front 44

escape()

Back 44

The escape() function encodes a string.

Front 45

eval()

Back 45

The eval() function evaluates or executes an argument.

Front 46

isFinite

Back 46

The isFinite() function determines whether a number is a finite, legal number.

Tip: This function returns false if the value is +infinity, -infinity, or NaN.

Front 47

isNaN()

Back 47

The isNaN() function determines whether a value is an illegal number (Not-a-Number).

Front 48

Number()

Back 48

The Number() function converts the object argument to a number that represents the object's value.

Front 49

parseFloat();

Back 49

The parseFloat() function parses a string and returns a floating point number.

Front 50

parseInt(string, rasdix)

Back 50

The parseInt() function parses a string and returns an integer.

The radix parameter is used to specify which numeral system to be used, for example, a radix of 16 (hexadecimal) indicates that the number in the string should be parsed from a hexadecimal number to a decimal number.

If the radix parameter is omitted, JavaScript assumes the following:

If the string begins with "0x", the radix is 16 (hexadecimal)
If the string begins with "0", the radix is 8 (octal). This feature is deprecated
If the string begins with any other value, the radix is 10 (decimal)

Front 51

String()

Back 51

The String() function converts the value of an object to a string.

Front 52

unescape(string)

Back 52

The unescape() function decodes an encoded string.

Front 53

What are the window Object Properties?

Back 53

1. closed
2. defaultStatus
3. document
4. frames
5. history
6. innerHeight
7. innerWidth
8. length
9. location
10. name
11. navigator
12. opener
13. outerWidth
14. outerHeight
15. pageXOffset
16. pageYOffset
17. parent
18. screen
19. screenLeft
20. screenTop
21. screenX
22. screenY
23. self
24. status
25. top

Front 54

window.closed()

Back 54

Returns a Boolean value indicating whether a window has been closed or not

Front 55

window.defaultStatus

Back 55

The defaultStatus property sets or returns the default text in the status bar at the bottom of the browser (the text will be displayed when the page loads).

example:
window.defaultStatus="This is the default text in the status bar!!"

Note: The defaultStatus property does not work in the default configuration of IE, Firefox, Chrome, or Safari. To allow scripts to change the text of the status, the user must set the dom.disable_window_status_change preference to false in the about:config screen. (or in Firefox: "Tools - Options - Content -Enable JavaScript / Advanced - Allow scripts to change status bar text").

Front 56

window.document

Back 56

Returns the Document object for the window

Front 57

window.frames

Back 57

Returns an array of all the frames (including iframes) in the current window

Front 58

window.history

Back 58

Returns the History object for the window

Front 59

window.innerHeight

Back 59

Sets or returns the inner height of a window's content area

Front 60

window.innerWidth

Back 60

Sets or returns the inner height of a window's content area

Front 61

window.length

Back 61

Returns the number of frames (including iframes) in a window

Front 62

window.location

Back 62

returns the location object

Front 63

window.name

Back 63

sets or returns the name of the window

Front 64

window.navigator

Back 64

Returns the navigator object for the window

Front 65

window.opener

Back 65

Returns the reference to the window that created the window

Front 66

window.outWidth

Back 66

Sets or returns the outer width of a window, including toolbars/scrollbars

Front 67

window.pageXOffset

Back 67

Returns the pixels the current document has been scrolled (horizontally) from the upper left corner of the window

Front 68

window.pageYOffset

Back 68

Returns the pixels the current document has been scrolled (vertically) from the upper left corner of the window

Front 69

window.parent

Back 69

Returns the parent window of the current window

Front 70

window.screen

Back 70

Returns the Screen object for the window (See Screen object)

Front 71

window.screenLeft

Back 71

Returns the x coordinate of the window relative to the screen

Front 72

window.screenY

Back 72

Returns the y coordinate of the window relative to the screen

Front 73

window.outerHeight

Back 73

Sets or returns the outer height of the window including toolbars /scrollbars

Front 74

window.screenTop

Back 74

Returns the y coordinate of the window relative to the screen

Front 75

window.screenY

Back 75

Returns the y coordinate of the window relative to the screen

Front 76

window.self

Back 76

Returns the current window

Front 77

window.status

Back 77

Sets the text in the statusbar of a window

Front 78

window.top

Back 78

returns the topmost browser window

Front 79

what are the window object methods?

Back 79

1. alert
2. blur
3. clearInterval
4. clearTimeout
5. close
6. createPopup
7. focus
8. moveBy
9. moveTo
10 open
11. print
12. prompt
13. resizeBy
14. resizeTo
15. scroll
16. scrollBy
17. scrollTo
18. setInterval
19. setTimeout

Front 80

window.blur()

Back 80

The blur() method removes focus from the current window.
The blur() method is supported in all major browsers, except Opera.

Front 81

window.clearInterval

Back 81

The clearInterval() method clears a timer set with the setInterval() method.

The ID value returned by setInterval() is used as the parameter for the clearInterval() method.

Syntax
clearInterval(id_of_setinterval)

Front 82

window.clearTimeout()

Back 82

The clearTimeout() method clears a timer set with the setTimeout() method.

Front 83

window.confirm()

Back 83

Definition and Usage
The confirm() method displays a dialog box with a specified message, along with an OK and a Cancel button.

This method returns true if the visitor clicked "OK", and false otherwise.

Syntax
confirm(message)

Browser Support
The confirm() method is supported in all major browsers.

Front 84

window.createPopup()

Back 84

Window createPopup() Method

Definition and Usage
The createPopup() method is used to create a pop-up window.

Syntax
window.createPopup()

Browser Support
Note: The createPopup() method is an IE-only method, and does not work in other browsers!

Front 85

window.focus()

Back 85

Definition and Usage
The focus() method sets focus to the current window.

Syntax
window.focus()

Browser Support
The focus() method is supported in all major browsers.

Front 86

window.moveBy()

Back 86

Definition and Usage
The moveBy() method moves a window a specified number of pixels relative to its current coordinates.

Syntax
window.moveBy(x,y)

Browser Support
The moveBy() method is supported in all major browsers.

Front 87

window.moveTo(x,y)

Back 87

Definition and Usage
The moveTo() method moves a window's left and top edge to the specified coordinates.

Syntax
window.moveTo(x,y)

Browser Support
The moveTo() method is supported in all major browsers.

Note: Specifying moveTo(0,0) in Opera, results in moving the window to the top left corner of the browser, not the screen.

Front 88

window.open()

Back 88

Definition and Usage
The open() method opens a new browser window.

Syntax
window.open(URL,name,specs,replace)

Browser Support
The open() method is supported in all major browsers.

Front 89

Describe the first parameter of the window.open function

Back 89

url : Optional. Specifies the URL of the page to open. If no URL is specified, a new window with about:blank is opened

Front 90

Describe the second parameter of the window.open function

Back 90

name: Optional. Specifies the target attribute or the name of the window. The following values are supported:
_blank - URL is loaded into a new window. This is default
_parent - URL is loaded into the parent frame
_self - URL replaces the current page
_top - URL replaces any framesets that may be loaded
name - The name of the window

Front 91

Describe the third parameter of the window.open function

Back 91

specs - A comma-separated list of items.
the items are
1.channel
2. directories
3. fullscreen
4. height
5. left
6. location
7. menubar
8. resizeable
9. scrollbars
10. titlebar
11. toolbar
12. top
13. width

Front 92

Describe the fourth parameter of the window.open function

Back 92

replace Optional.Specifies whether the URL creates a new entry or replaces the current entry in the history list. The following values are supported:
true - URL replaces the current document in the history list
false - URL creates a new entry in the history list

Front 93

window.print()

Back 93

Definition and Usage
The print() method prints the contents of the current window.

Syntax
window.print()

Browser Support
The print() method is supported in all major browsers.

Front 94

window.setInterval()

Back 94

Definition and Usage
The setInterval() method calls a function or evaluates an expression at specified intervals (in milliseconds).

The setInterval() method will continue calling the function until clearInterval() is called, or the window is closed.

The ID value returned by setInterval() is used as the parameter for the clearInterval() method.

Tip: 1000 ms = 1 second.

Syntax
setInterval(code,millisec,lang)

Parameter Description
code Required. The function that will be executed
millisec Required. The intervals (in milliseconds) on how often to execute the code
lang Optional. JScript | VBScript | JavaScript

Browser Support


The setInterval() method is supported in all major browsers.

Front 95

Properties of the location object

Back 95

1. hash
2. host
3. hostname
4. href
5. pathname
6. port
7. protocol
8. search

Front 96

location.hash

Back 96

Definition and Usage
The hash property returns the anchor portion of a URL, including the hash sign (#).

Syntax
location.hash

Browser Support
The hash property is supported in all major browsers.

Front 97

location.host

Back 97

Definition and Usage
The host property returns the hostname and port of a URL.

Syntax
location.host

Browser Support


The host property is supported in all major browsers.

Front 98

location.hostname

Back 98

Definition and Usage
The host property returns the hostname of a URL.

Syntax
location.hostname

Browser Support


The hostname property is supported in all major browsers.

Front 99

location.href

Back 99

Definition and Usage
The href property returns the entire URL of the current page.

Syntax
location.href

Browser Support
The href property is supported in all major browsers.

Front 100

location.pathname

Back 100

Definition and Usage
The pathname property returns the path name of a URL.

Syntax
location.pathname

Browser Support
The pathname property is supported in all major browsers.

Front 101

location.port

Back 101

Definition and Usage
The port property returns the port number the server uses for a URL.

Note: If the port number is 80 (which is the default port number), it is not specified.

Syntax
location.port

Browser Support
The port property is supported in all major browsers.

Front 102

location.protocol

Back 102

Definition and Usage
The protocol property returns the protocol of the current URL, including the first colon (:).

Syntax
location.protocol

Browser Support
The protocol property is supported in all major browsers.

Front 103

location.search

Back 103

Definition and Usage
The search property returns the query portion of a URL, including the question mark (?).

Syntax
location.search

Browser Support
The search property is supported in all major browsers.

Front 104

What are the location object methods

Back 104

1. assign
2. reload
3. replace

Front 105

location.assign(URL)

Back 105

Definition and Usage
The assign() method loads a new document.

Syntax
location.assign(URL)

Browser Support
The assign() method is supported in all major browsers.

Front 106

location.reload()

Back 106

Definition and Usage
The reload() method is used to reload the current document.

The reload() method does the same as the reload button in your browser.

By default, the reload() method reloads from the cache, but by you can force the the reload to get the page from server by setting the forceGet parameter to true.

Browser Support
The reload() method is supported in all major browsers.

Front 107

location.replace(newURL)

Back 107

Definition and Usage
The replace() method replaces the current document with a new one.

Syntax
location.replace(newURL)

Browser Support
The replace() method is supported in all major browsers.

Front 108

What are the Navigator properties

Back 108

1. appCodeName
2. appName
3. appVersion
4. cookieEnabled
5. onLine
6. platform
7. userAgent

Front 109

navigator.appCodeName

Back 109

Definition and Usage
The appCodeName property returns the code name of the browser.

Syntax
navigator.appCodeName

Browser Support


The appCodeName property is supported in all major browsers.

Front 110

navigator.appName

Back 110

Definition and Usage
The appName property returns the name of the browser.

Syntax
navigator.appName

Browser Support


The appName property is supported in all major browsers.

Front 111

navigator.appVersion

Back 111

Definition and Usage
The appVersion property returns the version information of the browser.

Syntax
navigator.appVersion

Browser Support


The appVersion property is supported in all major browsers.

Front 112

navigator.cookieEnabled

Back 112

Definition and Usage
The cookieEnabled property returns a Boolean value that specifies whether cookies are enabled in the browser.

Syntax
navigator.cookieEnabled

Browser Support
The cookieEnabled property is supported in all major browsers.

Front 113

navigator.onLine

Back 113

Definition and Usage
The onLine property returns a Boolean value that specifies whether the system is in offline mode.

Syntax
navigator.onLine

Browser Support
The onLine property is supported in all major browsers.

Front 114

navigator.platform

Back 114

Definition and Usage
The platform property returns for which platform the browser is compiled.

Syntax
navigator.platform

Browser Support


The platform property is supported in all major browsers.

Front 115

navigator.userAgent

Back 115

Definition and Usage
The userAgent property returns the value of the user-agent header sent by the browser to the server.

Syntax
navigator.userAgent

Browser Support


The userAgent property is supported in all major browsers.

Front 116

What are the Navigator Object Methods?

Back 116

1. javaEnabled
2. taintEnabled

Front 117

navigator.javaEnabled()

Back 117

Definition and Usage
The javaEnabled() method returns a Boolean value that specifies whether the browser has Java enabled.

Syntax
navigator.javaEnabled()

Browser Support


The javaEnabled() method is supported in all major browsers.

Front 118

navigator.taintEnabled()

Back 118

Definition and Usage
The taintEnabled() method returns a Boolean value that specifies whether the browser has data tainting enabled.

Syntax
navigator.taintEnabled()

Browser Support


The taintEnabled() method is supported in Internet Explorer and Opera.

Front 119

What are the Screen Object properties?

Back 119

1. availHeight
2. availWidth
3. colorDepth
4. height
5. width
6. pixelDepth

Front 120

screen.availHeight

Back 120

Definition and Usage
The availHeight property returns the height of the visitor's screen, in pixels, minus interface features like the Windows Taskbar.

Syntax
screen.availHeight

Browser Support


The availHeight property is supported in all major browsers.

Front 121

screen.availWidth

Back 121

Definition and Usage
The availWidth property returns the width of the visitor's screen, in pixels, minus interface features like the Windows Taskbar.

Syntax
screen.availWidth

Browser Support


The availWidth property is supported in all major browsers.

Front 122

screen.colorDepth

Back 122

Definition and Usage
The colorDepth property returns the bit depth of the color palette for displaying images (in bits per pixel).

Syntax
screen.colorDepth

Browser Support


The colorDepth property is supported in all major browsers.

Front 123

screen.height

Back 123

Definition and Usage
The height property returns the total height of the visitor's screen, in pixels.

Syntax
screen.height

Browser Support


The height property is supported in all major browsers.

Front 124

screen.pixelDepth

Back 124

Definition and Usage
The pixelDepth property returns the color resolution (in bits per pixel) of the visitor's screen.

Syntax
screen.pixelDepth

Browser Support


The pixelDepth property is supported in all major browsers, except Internet Explorer.

Tip: The colorDepth property represents the same thing as the pixelDepth property. Since all major browsers support colorDepth, use that property instead.

Front 125

screen.width

Back 125

Definition and Usage
The width property returns the total width of the visitor's screen, in pixels.

Syntax
screen.width

Browser Support


The width property is supported in all major browsers.

Front 126

window.setTimeout()

Back 126

Definition and Usage
The setTimeout() method calls a function or evaluates an expression after a specified number of milliseconds.

Tip: 1000 ms = 1 second.

Syntax
setTimeout(code,millisec,lang)

Parameter Description
code Required. The function that will be executed
millisec Required. The number of milliseconds to wait before executing the code
lang Optional. The scripting language: JScript | VBScript | JavaScript

Browser Support


The setTimeout() method is supported in all major browsers.

Front 127

What are the methods for the screen object?

Back 127

there are none

Front 128

What are the properties for the history object

Back 128

length

Front 129

history.length

Back 129

Definition and Usage
The length property returns the number of URLs in the history list.

Note: Internet Explorer and Opera start at 0, while Firefox, Chrome, and Safari start at 1.

Syntax
history.length

Browser Support


The length property is supported in all major browsers.

Front 130

What are the methods for the history object?

Back 130

1. back
2. forward
3. go

Front 131

history.back()

Back 131

Definition and Usage
The back() method loads the previous URL in the history list.

This is the same as clicking the Back button or history.go(-1).

Syntax
history.back()

Browser Support


The back() method is supported in all major browsers.

Front 132

history.forward()

Back 132

Definition and Usage
The forward() method loads the next URL in the history list.

This is the same as clicking the Forward button or history.go(1).

Syntax
history.forward()

Browser Support


The forward() method is supported in all major browsers.

Front 133

history.go()

Back 133

Definition and Usage
The go() method loads a specific URL from the history list.

The parameter can either be a number which goes to the URL within the specific position (-1 goes back one page, 1 goes forward one page), or a string. The string must be a partial or full URL, and the function will go to the first URL that matches the string.

Syntax
history.go(number|URL)

Browser Support


The go() method is supported in all major browsers.