Merge branch 'master' of https://github.com/adambard/learnxinyminutes-docs

1 files changed, 46 insertions, 14 deletions

diff --git a/javascript.html.markdown b/javascript.html.markdown
index ba2e8ce4..a119be88 100644
--- a/javascript.html.markdown
+++ b/javascript.html.markdown
@@ -54,6 +54,11 @@ 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
@@ -64,7 +69,7 @@ doStuff()
 // There are three special not-a-real-number values:
 Infinity; // result of e.g. 1/0
 -Infinity; // result of e.g. -1/0
-NaN; // result of e.g. 0/0
+NaN; // result of e.g. 0/0, stands for 'Not a Number'
 
 // There's also a boolean type.
 true;
@@ -104,7 +109,7 @@ 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 +149,10 @@ 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
@@ -189,7 +198,7 @@ myObj.myFourthKey; // = undefined
 ///////////////////////////////////
 // 3. Logic and Control Structures
 
-// The syntax for this section is almost identical to Java's. 
+// The syntax for this section is almost identical to Java's.
 
 // The `if` structure works as you'd expect.
 var count = 1;
@@ -218,6 +227,26 @@ for (var i = 0; i < 5; i++){
     // will run 5 times
 }
 
+//The For/In statement loops iterates over every property across the entire prototype chain
+var description = "";
+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,
+//and not its prototypes use hasOwnProperty() check
+var description = "";
+var person = {fname:"Paul", lname:"Ken", age:18};
+for (var x in person){
+    if (person.hasOwnProperty(x)){
+        description += person[x] + " ";
+    }
+}
+
+//for/in should not be used to iterate over an Array where the index order is important.
+//There is no guarantee that for/in will return the indexes in any particular order
+
 // && is logical and, || is logical or
 if (house.size == "big" && house.colour == "blue"){
     house.contains = "bear";
@@ -231,8 +260,8 @@ var name = otherName || "default";
 
 
 // The `switch` statement checks for equality with `===`.
-// use 'break' after each case 
-// or the cases after the correct one will be executed too. 
+// use 'break' after each case
+// or the cases after the correct one will be executed too.
 grade = 'B';
 switch (grade) {
   case 'A':
@@ -262,12 +291,9 @@ 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
 
@@ -281,6 +307,12 @@ 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(){
@@ -299,7 +331,7 @@ 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;
@@ -393,7 +425,7 @@ 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(){
@@ -516,12 +548,12 @@ 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)
 
-[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. 
+[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. 
+[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