Bold Object The Bold object represents an HTML <b> element. Access a Bold Object You can access a <b> element by using getElementById(): Example var x = document.getElementById(“myB”); Try it Yourself » Create a Bold Object You can create a <b> element by using the document.createElement() method: Example var x = document.createElement(“B”); Try it Yourself » Standard […]
Small Object The Small object represents an HTML <small> element. Access a Small Object You can access a <small> element by using getElementById(): Example var x = document.getElementById(“mySmall”); Try it Yourself » Create a Small Object You can create a <small> element by using the document.createElement() method: Example var x = document.createElement(“SMALL”); Try it Yourself » Standard […]
Example A video with two subtitle tracks: <video width=”320″ height=”240″ controls> <source src=”forrest.mp4″ type=”video/mp4″> <track src=”subtitles_en.vtt” kind=”subtitles” srclang=”en” label=”English”> <track src=”subtitles_no.vtt” kind=”subtitles” srclang=”no” label=”Norwegian”> </video> Definition and Usage The srclang attribute specifies the language of the track text data. This attribute is required if kind=”subtitles”. Tip: To view all available language codes, go to our Language code reference. Browser Support The numbers in the table specify the first browser version […]
DList Object The DList object represents an HTML <dl> element. Access a DList Object You can access a <dl> element by using getElementById(): Example var x = document.getElementById(“myDL”); Try it Yourself » Create a DList Object You can create a <dl> element by using the document.createElement() method: Example var x = document.createElement(“DL”); Try it Yourself » Standard […]
Example Set the background color of the first two columns using the <colgroup> span attribute: <table> <colgroup span=”2″ style=”background:red”></colgroup> <tr> <th>ISBN</th> <th>Title</th> <th>Price</th> </tr> <tr> <td>3476896</td> <td>My first HTML</td> <td>$53</td> </tr> <tr> <td>5869207</td> <td>My first CSS</td> <td>$49</td> </tr> </table> Try it Yourself » Definition and Usage The span attribute defines the number of columns a <colgroup> element […]
Example Set the background color of the three columns with the <colgroup> and <col> tags: <table> <colgroup> <col span=”2″ style=”background-color:red”> <col style=”background-color:yellow”> </colgroup> <tr> <th>ISBN</th> <th>Title</th> <th>Price</th> </tr> <tr> <td>3476896</td> <td>My first HTML</td> <td>$53</td> </tr> </table> Try it Yourself » Definition and Usage The <col> tag specifies column properties for each column within a <colgroup> element. The <col> tag is […]
Example Draw a red square, on the fly, and show it inside the <canvas> element: <canvas id=”myCanvas”></canvas> <script> var canvas = document.getElementById(“myCanvas”); var ctx = canvas.getContext(“2d”); ctx.fillStyle = “#FF0000”; ctx.fillRect(0, 0, 80, 80); </script> Try it Yourself » Definition and Usage The <canvas> tag is used to draw graphics, on the fly, via scripting (usually JavaScript). The <canvas> tag is only a container […]
Style Guide and Coding Conventions HTML Coding Conventions Web developers are often uncertain about the coding style and syntax to use in HTML. Between 2000 and 2010, many web developers converted from HTML to XHTML. With XHTML, developers were forced to write valid and “well-formed” code. HTML5 is a bit more sloppy when it comes […]
Avoid global variables, avoid new, avoid ==, avoid eval() Avoid Global Variables Minimize the use of global variables. This includes all data types, objects, and functions. Global variables and functions can be overwritten by other scripts. Use local variables instead, and learn how to use closures. Always Declare Local Variables All variables used in a function […]
Always use the same coding conventions for all your JavaScript projects. JavaScript Coding Conventions Coding conventions are style guidelines for programming. They typically cover: Naming and declaration rules for variables and functions. Rules for the use of white space, indentation, and comments. Programming practices and principles Coding conventions secure quality: Improves code readability Make code maintenance easier […]
Math.random() Math.random() returns a random number between 0 (inclusive), and 1 (exclusive): Example Math.random(); // returns a random number Try it Yourself » Math.random() always returns a number lower than 1. JavaScript Random Integers Math.random() used with Math.floor() can be used to return random integers. Example Math.floor(Math.random() * 10); // returns a random integer from 0 to […]
JavaScript variables are containers for storing data values. In this example, x, y, and z, are variables: Example var x = 5; var y = 6; var z = x + y; Try it Yourself » From the example above, you can expect: x stores the value 5 y stores the value 6 z stores the value 11 Much Like […]
JavaScript comments can be used to explain JavaScript code, and to make it more readable. JavaScript comments can also be used to prevent execution, when testing alternative code. Single Line Comments Single line comments start with //. Any text between // and the end of the line will be ignored by JavaScript (will not be […]
The <script> Tag In HTML, JavaScript code must be inserted between <script> and </script> tags. Example <script> document.getElementById(“demo”).innerHTML = “My First JavaScript”; </script> Try it Yourself » Old JavaScript examples may use a type attribute: <script type=”text/javascript”>. The type attribute is not required. JavaScript is the default scripting language in HTML. JavaScript Functions and Events A JavaScript function is […]
This page contains some examples of what JavaScript can do. JavaScript Can Change HTML Content One of many JavaScript HTML methods is getElementById(). This example uses the method to “find” an HTML element (with id=”demo”) and changes the element content (innerHTML) to “Hello JavaScript”: document.getElementById(“demo”).innerHTML = “Hello JavaScript”; Try it Yourself » JavaScript accepts both double and single […]
Images can improve the design and the appearance of a web page. HTML Images Syntax In HTML, images are defined with the <img> tag. The <img> tag is empty, it contains attributes only, and does not have a closing tag. The src attribute specifies the URL (web address) of the image: <img src=”url“> The alt Attribute The alt attribute provides an alternate text for an […]
HTML List Example An Unordered List: Item Item Item Item An Ordered List: First item Second item Third item Fourth item Try it Yourself » Unordered HTML List An unordered list starts with the <ul> tag. Each list item starts with the <li> tag. The list items will be marked with bullets (small black circles) by default: Example <ul> […]
Using The class Attribute The class attribute specifies one or more class names for an HTML element. The class name can be used by CSS and JavaScript to perform certain tasks for elements with the specified class name. In CSS, to select elements with a specific class, write a period (.) character, followed by the name of […]
Using The id Attribute The id attribute specifies a unique id for an HTML element (the value must be unique within the HTML document). The id value can be used by CSS and JavaScript to perform certain tasks for a unique element with the specified id value. In CSS, to select an element with a specific id, […]
JavaScript makes HTML pages more dynamic and interactive. Example My First JavaScript Click me to display Date and Time Try it Yourself » The HTML <script> Tag The <script> tag is used to define a client-side script (JavaScript). The <script> element either contains scripting statements, or it points to an external script file through the src attribute. Common uses for JavaScript […]
