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Diffstat (limited to 'javascript.html.markdown')
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1 files changed, 48 insertions, 36 deletions
diff --git a/javascript.html.markdown b/javascript.html.markdown index 6ea0b0bb..cce488e1 100644 --- a/javascript.html.markdown +++ b/javascript.html.markdown @@ -16,12 +16,8 @@ JavaScript isn't just limited to web browsers, though: Node.js, a project that provides a standalone runtime for Google Chrome's V8 JavaScript engine, is becoming more and more popular. -Feedback would be highly appreciated! You can reach me at -[@adambrenecki](https://twitter.com/adambrenecki), or -[adam@brenecki.id.au](mailto:adam@brenecki.id.au). - ```js -// Comments are like C. Single-line comments start with two slashes, +// Comments are like C's. Single-line comments start with two slashes, /* and multiline comments start with slash-star and end with star-slash */ @@ -54,6 +50,11 @@ doStuff() // Including uneven division. 5 / 2; // = 2.5 +// And modulo division. +10 % 2; // = 0 +30 % 4; // = 2 +18.5 % 7; // = 4.5 + // Bitwise operations also work; when you perform a bitwise operation your float // is converted to a signed int *up to* 32 bits. 1 << 2; // = 4 @@ -104,7 +105,7 @@ null == undefined; // = true // ...unless you use === "5" === 5; // = false -null === undefined; // = false +null === undefined; // = false // ...which can result in some weird behaviour... 13 + !0; // 14 @@ -144,6 +145,10 @@ someOtherVar = 10; // Variables declared without being assigned to are set to undefined. var someThirdVar; // = undefined +// if you wan't to declare a couple of variables, then you could use a comma +// separator +var someFourthVar = 2, someFifthVar = 4; + // There's shorthand for performing math operations on variables: someVar += 5; // equivalent to someVar = someVar + 5; someVar is 10 now someVar *= 10; // now someVar is 100 @@ -220,15 +225,15 @@ for (var i = 0; i < 5; i++){ //The For/In statement loops iterates over every property across the entire prototype chain var description = ""; -var person = {fname:"Paul", lname:"Ken", age:18}; +var person = {fname:"Paul", lname:"Ken", age:18}; for (var x in person){ description += person[x] + " "; } -//If only want to consider properties attached to the object itself, +//If only want to consider properties attached to the object itself, //and not its prototypes use hasOwnProperty() check var description = ""; -var person = {fname:"Paul", lname:"Ken", age:18}; +var person = {fname:"Paul", lname:"Ken", age:18}; for (var x in person){ if (person.hasOwnProperty(x)){ description += person[x] + " "; @@ -282,12 +287,9 @@ myFunction("foo"); // = "FOO" // Note that the value to be returned must start on the same line as the // `return` keyword, otherwise you'll always return `undefined` due to // automatic semicolon insertion. Watch out for this when using Allman style. -function myFunction() -{ +function myFunction(){ return // <- semicolon automatically inserted here - { - thisIsAn: 'object literal' - } + {thisIsAn: 'object literal'} } myFunction(); // = undefined @@ -301,6 +303,12 @@ setTimeout(myFunction, 5000); // Note: setTimeout isn't part of the JS language, but is provided by browsers // and Node.js. +// Another function provided by browsers is setInterval +function myFunction(){ + // this code will be called every 5 seconds +} +setInterval(myFunction, 5000); + // Function objects don't even have to be declared with a name - you can write // an anonymous function definition directly into the arguments of another. setTimeout(function(){ @@ -319,7 +327,7 @@ i; // = 5 - not undefined as you'd expect in a block-scoped language // scope. (function(){ var temporary = 5; - // We can access the global scope by assiging to the "global object", which + // We can access the global scope by assigning to the "global object", which // in a web browser is always `window`. The global object may have a // different name in non-browser environments such as Node.js. window.permanent = 10; @@ -413,7 +421,7 @@ var doubler = product.bind(this, 2); doubler(8); // = 16 // When you call a function with the `new` keyword, a new object is created, and -// made available to the function via the this keyword. Functions designed to be +// made available to the function via the `this` keyword. Functions designed to be // called like that are called constructors. var MyConstructor = function(){ @@ -522,28 +530,32 @@ if (Object.create === undefined){ // don't overwrite it if it exists ## Further Reading -The [Mozilla Developer -Network](https://developer.mozilla.org/en-US/docs/Web/JavaScript) provides -excellent documentation for JavaScript as it's used in browsers. Plus, it's a -wiki, so as you learn more you can help others out by sharing your own -knowledge. +The [Mozilla Developer Network][1] provides excellent documentation for +JavaScript as it's used in browsers. Plus, it's a wiki, so as you learn more you +can help others out by sharing your own knowledge. + +MDN's [A re-introduction to JavaScript][2] covers much of the concepts covered +here in more detail. This guide has quite deliberately only covered the +JavaScript language itself; if you want to learn more about how to use +JavaScript in web pages, start by learning about the [Document Object Model][3]. + +[Learn Javascript by Example and with Challenges][4] is a variant of this +reference with built-in challenges. -MDN's [A re-introduction to -JavaScript](https://developer.mozilla.org/en-US/docs/Web/JavaScript/A_re-introduction_to_JavaScript) -covers much of the concepts covered here in more detail. This guide has quite -deliberately only covered the JavaScript language itself; if you want to learn -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][5] is an in-depth guide of all the counter-intuitive parts +of the language. -[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: The Definitive Guide][6] is a classic guide and reference book. -[JavaScript Garden](http://bonsaiden.github.io/JavaScript-Garden/) is an in-depth -guide of all the counter-intuitive parts of the language. +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][7] on the +Mozilla Developer Network. -[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) -on the Mozilla Developer Network. +[1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript +[2]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/A_re-introduction_to_JavaScript +[3]: https://developer.mozilla.org/en-US/docs/Using_the_W3C_DOM_Level_1_Core +[4]: http://www.learneroo.com/modules/64/nodes/350 +[5]: http://bonsaiden.github.io/JavaScript-Garden/ +[6]: http://www.amazon.com/gp/product/0596805527/ +[7]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/A_re-introduction_to_JavaScript |