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authorJacob Ward <jacobward1898@gmail.com>2015-10-26 23:03:37 -0600
committerJacob Ward <jacobward1898@gmail.com>2015-10-26 23:03:37 -0600
commita0eb996415cc86cb72c44e793ebfacc3ec2d7b17 (patch)
tree516c83684b752f374758b9abd3b89be723478fd3 /javascript.html.markdown
parent66bc42e31bf62a1592f9b763e12c0b963b3e7d3d (diff)
parent44ca091c73afe13ec8760021cfed1d77afc5e4a5 (diff)
Merge remote-tracking branch 'adambard/master'
Diffstat (limited to 'javascript.html.markdown')
-rw-r--r--javascript.html.markdown84
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