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Diffstat (limited to 'javascript.html.markdown')
| -rw-r--r-- | javascript.html.markdown | 53 |
1 files changed, 45 insertions, 8 deletions
diff --git a/javascript.html.markdown b/javascript.html.markdown index 7fb7ba55..76017c17 100644 --- a/javascript.html.markdown +++ b/javascript.html.markdown @@ -2,10 +2,11 @@ language: javascript contributors: - ["Adam Brenecki", "http://adam.brenecki.id.au"] + - ["Ariel Krakowski", "http://www.learneroo.com"] filename: javascript.js --- -Javascript was created by Netscape's Brendan Eich in 1995. It was originally +JavaScript was created by Netscape's Brendan Eich in 1995. It was originally intended as a simpler scripting language for websites, complimenting the use of Java for more complex web applications, but its tight integration with Web pages and built-in support in browsers has caused it to become far more common than @@ -37,7 +38,7 @@ doStuff() /////////////////////////////////// // 1. Numbers, Strings and Operators -// Javascript has one number type (which is a 64-bit IEEE 754 double). +// JavaScript has one number type (which is a 64-bit IEEE 754 double). // As with Lua, don't freak out about the lack of ints: doubles have a 52-bit // mantissa, which is enough to store integers up to about 9✕10¹⁵ precisely. 3; // = 3 @@ -103,7 +104,13 @@ false; "5" === 5; // = false // You can access characters in a string with charAt -"This is a string".charAt(0); +"This is a string".charAt(0); // = 'T' + +// ...or use substring to get larger pieces +"Hello world".substring(0, 5); // = "Hello" + +// length is a property, so don't use () +"Hello".length; // = 5 // There's also null and undefined null; // used to indicate a deliberate non-value @@ -116,7 +123,7 @@ undefined; // used to indicate a value is not currently present (although /////////////////////////////////// // 2. Variables, Arrays and Objects -// Variables are declared with the var keyword. Javascript is dynamically typed, +// Variables are declared with the var keyword. JavaScript is dynamically typed, // so you don't need to specify type. Assignment uses a single = character. var someVar = 5; @@ -148,6 +155,9 @@ myArray[1]; // = 45 myArray.push("World"); myArray.length; // = 4 +// Add/Modify at specific index +myArray[3] = "Hello"; + // JavaScript's objects are equivalent to 'dictionaries' or 'maps' in other // languages: an unordered collection of key-value pairs. var myObj = {key1: "Hello", key2: "World"}; @@ -171,18 +181,20 @@ myObj.myFourthKey; // = undefined /////////////////////////////////// // 3. Logic and Control Structures +// The syntax for this section is almost identical to Java's. + // The if structure works as you'd expect. var count = 1; if (count == 3){ // evaluated if count is 3 -} else if (count == 4) { +} else if (count == 4){ // evaluated if count is 4 } else { // evaluated if it's not either 3 or 4 } // As does while. -while (true) { +while (true){ // An infinite loop! } @@ -209,6 +221,27 @@ if (colour == "red" || colour == "blue"){ // && and || "short circuit", which is useful for setting default values. var name = otherName || "default"; + +// switch statement checks for equality with === +// use 'break' after each case +// or the cases after the correct one will be executed too. +grade = 'B'; +switch (grade) { + case 'A': + console.log("Great job"); + break; + case 'B': + console.log("OK job"); + break; + case 'C': + console.log("You can do better"); + break; + default: + console.log("Oy vey"); + break; +} + + /////////////////////////////////// // 4. Functions, Scope and Closures @@ -327,7 +360,7 @@ var anotherFunc = function(s){ } anotherFunc.call(myObj, " And Hello Moon!"); // = "Hello World! And Hello Moon!" -// The 'apply' function is nearly identical, but takes an array for an argument list. +// The 'apply' function is nearly identical, but takes an array for an argument list. anotherFunc.apply(myObj, [" And Hello Sun!"]); // = "Hello World! And Hello Sun!" @@ -477,9 +510,13 @@ more about how to use JavaScript in web pages, start by learning about the [Document Object Model](https://developer.mozilla.org/en-US/docs/Using_the_W3C_DOM_Level_1_Core) -[Javascript Garden](http://bonsaiden.github.io/JavaScript-Garden/) is an in-depth +[Learn Javascript by Example and with Challenges](http://www.learneroo.com/modules/64/nodes/350) is a variant of this reference with built-in challenges. + +[JavaScript Garden](http://bonsaiden.github.io/JavaScript-Garden/) is an in-depth guide of all the counter-intuitive parts of the language. +[JavaScript: The Definitive Guide](http://www.amazon.com/gp/product/0596805527/) is a classic guide / reference book. + In addition to direct contributors to this article, some content is adapted from Louie Dinh's Python tutorial on this site, and the [JS Tutorial](https://developer.mozilla.org/en-US/docs/Web/JavaScript/A_re-introduction_to_JavaScript) |