The tables you find here offer a one-stop reference for the most common programming variables, commands, methods, and coding miscellany used in JavaScript programs, jQuery, and AJAX.
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Code to Use in JavaScript Variable Manipulation Functions
As shown in the following table, you can use these JavaScript statements in your own code to create and modify variables in your JavaScript functions.
| Element | Description |
|---|---|
| var myVar = 0; | Creates a variable with given starting value. Type is determined dynamically. |
| stringVar = prompt("message") | Sends message to user in a dialog box, retrieves text input from user and stores it in stringVar. |
| stringVar.length | Returns the length (in characters) of stringVar. |
| stringVar.toUpperCase(), stringVar.toLowerCase() | Converts stringVar to upper- or lowercase. |
| stringVar.substring() | Returns a specified subset of stringVar. |
| stringVar.indexOf() | Returns location of a substring in stringVar (or -1). |
| parseInt() | Converts string to int. |
| parseFloat() | Converts string to float. |
| toString() | Converts any variable to string. |
| eval() | Evaluates string as JavaScript code. |
| Math.ceil() | Converts any number to integer by rounding up. |
| Math.floor() | Converts any number to integer by rounding down. |
| Math.round() | Converts any number to integer by standard rounding algorithm. |
| Math.random() | Returns random float between 0 and 1. |
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Basic I/O Commands in JavaScript
JavaScript programmers commonly use the commands shown in the following table for controlling dialog-based input and output in programs to be used on the Web.
| Element | Description |
|---|---|
| alert("message"); | Creates a popup dialog containing "message." |
| stringVar = prompt("message") | Send message to user in a dialog box, retrieve text input from user and store it in stringVar. |
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JavaScript Conditions and Branching Code Structures
Look to the following table for JavaScript control structures you can use in your program code to add branching and looping behavior to your JavaScript programs.
| Element | Description |
|---|---|
| if (condition){ // content } else { // more content } // end if | Executes content only if condition is true. Optional else clause occurs if condition is false. |
| switch (expression) case: value; //code break; default: //code } | Compares expression against one or more values. If expression is equal to value, runs corresponding code. Default clause catches any uncaught values. |
| for(i = 0; i < count; i++) //code } // end for | Repeats code i times. |
| While (condition){ //code } // end while | Repeats code as long as condition is true. |
| Function fnName(paramaters) { //code } // end function | Defines a function named fnName and sends it parameters. All code inside the function will execute when the function is called. |
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Add JavaScript Comparison Operators to Condition Statements
JavaScript uses comparison operators inside conditions to make numeric or alphabetical comparisons of variables to other variables or values. Using these operators, you can determine whether a variable is greater than, less than, or equal to another variable or value. You can also use combinations of these comparison operators.
| Name | Operator | Example | Notes |
|---|---|---|---|
| Equality | == | (x==3) | Works with all variable types, including strings. |
| Not equal | != | (x != 3) | True if values are not equal. |
| Less than | < | (x < 3) | Numeric or alphabetical comparison. |
| Greater than | > | (x > 3) | Numeric or alphabetical comparison. |
| Less than or equal to | <= | (x <= 3) | Numeric or alphabetical comparison. |
| Greater than or equal to | >= | (x >= 3) | Numeric or alphabetical comparison. |
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Create JavaScript Structures and Objects
JavaScript allows you to put together code lines to create functions and variables to create arrays. You can put functions and variables together to create objects.
| Element | Description |
| function fnName(parameters) { //code } // end function | Defines a function named fnName and sends it parameters. All code inside function will execute when the function is called. |
| var myArray = new Array("a", "b", "c"); | Creates an array. Elements can be any type (even mixed types). |
| Var myJSON = { "name": "Andy", "title": "Author" } | Creates a JSON object. Each element has a name/value pair, and can contain anything, including an array (with square braces) another JSON object, or a function. |
| Var person = new Object(); Person.name = "Andy"; | Creates an object. You can add ordinary variables (which become properties) or functions (which become methods). |
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Change Your Web Page with JavaScript Document Object Model Methods
The Document Object Model methods shown in the following table offer you a great way to access and modify your Web pages through your JavaScript code.
| Element | Description |
| myElement = document.getElementById("name"); | Gets an element from the page with the specified ID and copies a reference to that element to the variable myElement. |
| myElement.innerHTML = "value" | Changes the value of the element to "value". |
| document.onkeydown = keyListener | When a key is pressed, a function called keyListener is automatically activated. |
| document.onmousemove = mouseListener | When the mouse is moved, a function called mouseListener is automatically activated. |
| setInterval(function, ms); | Runs function each ms milliseconds. |
| myArray = document.getElementsByName("name") | Returns an array of objects with the current name (frequently used with radio buttons). |
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Add Searching Tools with Regular Expression Operators in JavaScript
The regular expression mechanism adds extremely powerful searching tools to your programming. Here are some of the most commonly used regular expressions as they are used in JavaScript.
| Operator | Description | Sample pattern | matches | Doesn’t match |
| . (period) | Any single character except | . | E | \n |
| ^ | Beginning of string | ^a | apple | Banana |
| $ | End of string | a$ | banana | Apple |
| [characters] | Any of a list of characters in braces | [abcABC] | A | D |
| [char range] | Any character in the range | [a-zA-Z] | F | 9 |
| \d | Any single numerical digit | \d\d\d-\d\d\d\d | 123-4567 | The-thing |
| \b | A word boundary | \bthe\b | the | Theater |
| + | One or more occurrences of the previous character | \d+ | 1234 | Text |
| * | Zero or more occurrences of the previous character | [a-zA-Z]d* | B17, g | 7 |
| {digit} | Repeat preceding character digit times | \d{3}-\d{4} | 123-4567 | 999-99-9999 |
| {min, max} | Repeat preceding character at least min but not more than max times | .{2,4} | Ca, com, info | watermelon |
| (pattern segment) | Store results in pattern memory returned with code | ^(.).*\1$ | gig, wallow | Bobby |
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Common Methods of the jQuery Node
The jQuery library turns DOM objects into powerful jQuery nodes. The following table shows a few of the more commonly used methods of the jQuery node.
| Method | Description |
| addClass(), removeClass(), toggleClass() | Applies or removes a CSS class to a jQuery node. |
| css("attribute", "value") | Applies a single CSS rule to the jQuery node. |
| Css(JSONObject) | Applies JSON object list of CSS rules and values to the jQuery node. |
| html() | Reads or changes the HTML contents of the jQuery node. |
| text() | Reads or changes the text contents of a jQuery node. |
| val() | Reads the value of a form element. |
| bind(event, function) | Triggers function to occur when event occurs. |
| Show(), hide(), toggle() | Makes element appear or disappear. |
| animate(parameters, duration) | parameters is a JSON object consisting of CSS rules and values. Values are smoothly changed from current value to target value over duration (measured in milliseconds). |
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jQuery Selectors and Filters
Part of jQuery’s power is based on its ability to select particular sections of the page. This table includes several commonly used selectors and filters.
| Selector/Filter | Searches for… |
| $("element") | Any HTML element. |
| $("#elementID") | Any element with the given ID. |
| $(".className") | Any element with the given class name. |
| :header | Any header tag (h1, h2, h3, and so on). |
| :animated | Any element that is currently being animated. |
| :contains(text) | Any element that contains the indicated text. |
| :empty | The element is empty. |
| :parent | An element that contains some other element. |
| :attribute=value | The element has an attribute with the specified value. |
| :Input, :text, :radio, :image, :button, etc | Matches on the specific element type (especially useful for form elements that are all variations of the |
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Add jQuery User Interface Classes to Theme Styles
These CSS classes are defined in a jQuery UI theme. If you’re using jQuery UI, you can add any of these classes to your objects to add the theme styles.
| Class | Used on | Description |
| ui-widget | Outer container of widget | Makes element look like a widget. |
| ui-widget-header | Heading element | Applies distinctive heading appearance. |
| ui-widget-content | Widget | Applies widget content style to element and children. |
| ui-state-default | Clickable elements | Displays standard (unclicked) state. |
| ui-state-hover | Clickable elements | Displays hover state. |
| ui-state-focus | Clickable elements | Display focus state when element has keyboard focus. |
| ui-state-active | Clickable elements | Display active state when mouse is clicked on element. |
| ui-state-highlight | Any widget or element | Specifies element is currently highlighted. |
| ui-state-error | Any widget or element | Specifies an element will contain an error or warning message. |
| ui-state-error text | Text element | Allows error highlighting without changing other elements (mainly used in form validation). |
| ui-state-disabled | Any widget or element | Demonstrates that widget is currently disabled. |
| ui-corner-all, ui-corner-tl (etc) | Any widget or element | Adds current corner size to element. Specify specific corners with tl, tr, bl, br, top, bottom, left, right. |
| ui-widget-shadow | Any widget | Applies shadow effect to widget. |
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jQuery Methods for Sending an AJAX Request
As you can see from studying the following table, jQuery supplies several methods for sending an AJAX request to the server and parsing the results.
| Method | Description |
| get(url, parameters) | Send an HTTP GET request to the given URL. Parameters is JSON object encapsulating form data (name/value pairs). Result is returned as HTML, XML, or plain text data. |
| post(url, parameters) | Just like get, but uses the |
| load(url, parameters) | Much like get(), but returns a jQuery object. Calling jQuery objects contents are replaced by the returned data (usually HTML or XHTML). |
| getJSON | Like get, but returns a JSON object, which can be parsed for further processing. |
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Source:http://www.dummies.com/how-to/content/javascript-ajax-for-dummies-cheat-sheet.html
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