shaunwallace

function double(element, index, array) {
    console.log('elem['+ index + '] ', element * 2);
}

[1,2,3,4,5].foEach(double); // returns elem[0] 2 elem[1] 4 elem[2] 6 elem[3] 8 elem[4] 10 

shaunwallace

function isBigEnough(element, index, array) {
    return element >= 10;
}

[12, 5, 8, 130, 44].filter(isBigEnough); // returns [12,130,44]

shaunwallace

function isBigEnough(element, index, array) {
    return element >= 10;
}

var passed = [12, 5, 8, 130, 44].every(isBigEnough); // passed is false
passed = [12, 54, 18, 130, 44].every(isBigEnough); // passed is true

shaunwallace

// all following calls return true
Array.isArray([]);
Array.isArray([1]);
Array.isArray(new Array());

// all following calls return false
Array.isArray();
Array.isArray({});
Array.isArray(null);
Array.isArray(undefined);

shaunwallace

var trimmed = '     foo     ';
trimmed = trimmed.trim(); // returns 'foo'

// ES5 also allows for access to characters at specific indices via the bracket notation 

trimmed[0]; // returns "f"

shaunwallace

function Shape() {
    this.width = 100;
    this.height = 100;
}

Shape.prototype.area = function() {
    return this.width * this.height;
}

var square = new Shape();

shaunwallace

var obj13 = Object.create({});
obj13.foo = 'x';
obj13.bar = 'y';

Object.freeze( obj13 ); // freezes the object completely

Object.isFrozen( obj13 ); // returns true

Object.isFrozen({}); // returns false because a newly created object is extensible by default

shaunwallace

// create empty object
var obj13 = Object.create({});
// adding some properties
obj13.foo = 'x';
obj13.bar = 'y';
Object.freeze( obj13 ); // freezes the object completely

// after being frozen we can not alter the object
obj13.baz = 'z';
obj13.foo = false;

shaunwallace

var obj12 = { foo : 200 };

obj12.foo = false;
obj12; // returns false
Object.seal( obj12 );
obj12.foo = 100;
obj12.foo; // returns 100
delete obj12.foo; // returns false

shaunwallace

var obj11 = Object.create(Object.prototype, { foo : {
        value : 27
    }, 
        bar : {
            value : 39,
            enumerable : true
        }
    });
    
Object.preventExtensions( obj11 );