[10] === 10 // is false
　　[10] == 10 // is true
　　'10' == 10 // is true
　　'10' === 10 // is false
　　 [] == 0 // is true
　　 [] === 0 // is false
　　 '' == false // is true but true == "a" is false
　　 '' === false // is false

　　function Person(firstName, lastName){
this.firstName = firstName;
this.lastName = lastName;
　　}
　　var Saad = new Person("Saad", "Mousliki");

var arr = ["a", "b", "c"];
　　typeof arr; // 返回 "object"
　　arr instanceof Array // true
　　arr.constructor(); //[]

　(function(){
// 置于此处的代码将自动执行
　　})(); 
　　(function(a,b){
var result = a+b;
return result;
　　})(10,20)

var items = [12, 548 , 'a' , 2 , 5478 , 'foo' , 8852, , 'Doe' , 2145 , 119];
var randomItem = items[Math.floor(Math.random() * items.length)];

var x = Math.floor(Math.random() * (max - min + 1)) + min;

var numbersArray = [] , max = 100;
　　for( var i=1; numbersArray.push(i++) < max;); // numbers = [1,2,3 ... 100]

　　function generateRandomAlphaNum(len) {
var rdmString = "";
for( ; rdmString.length < len; rdmString += Math.random().toString(36).substr(2));
return rdmString.substr(0, len);
　　}

var numbers = [5, 458 , 120 , -215 , 228 , 400 , 122205, -85411];
　　numbers = numbers.sort(function(){ return Math.random() - 0.5});
　　/* numbers 数组将类似于 [120, 5, 228, -215, 400, 458, -85411, 122205] */

String.prototype.trim = function(){return this.replace(/^\s+|\s+$/g, "");};

　　var array1 = [12 , "foo" , {name "Joe"} , -2458];
　　var array2 = ["Doe" , 555 , 100];
　　Array.prototype.push.apply(array1, array2);
　　/* array1 值为 [12 , "foo" , {name "Joe"} , -2458 , "Doe" , 555 , 100] */

var argArray = Array.prototype.slice.call(arguments);

function isNumber(n){
return !isNaN(parseFloat(n)) && isFinite(n);
　　}

　　function isArray(obj){
return Object.prototype.toString.call(obj) === '[object Array]' ;
　　}

Array.isArray(obj); // its a new Array method

var myFrame = document.createElement('iframe');
　　document.body.appendChild(myFrame);
　　var myArray = window.frames[window.frames.length-1].Array;
　　var arr = new myArray(a,b,10); // [a,b,10] 
　　// myArray 的构造器已经丢失，instanceof 的结果将不正常
　　// 构造器是不能跨 frame 共享的
　　arr instanceof Array; // false

　var numbers = [5, 458 , 120 , -215 , 228 , 400 , 122205, -85411];
　　var maxInNumbers = Math.max.apply(Math, numbers);
　　var minInNumbers = Math.min.apply(Math, numbers);

var myArray = [12 , 222 , 1000 ]; 
　　myArray.length = 0; // myArray will be equal to [].

　var items = [12, 548 ,'a' , 2 , 5478 , 'foo' , 8852, , 'Doe' ,2154 , 119 ];
　　items.length; // return 11
　　delete items[3]; // return true
　　items.length; // return 11
　　/* items 结果为 [12, 548, "a", undefined × 1, 5478, "foo", 8852, undefined × 1, "Doe", 2154, 119] */

　　var items = [12, 548 ,'a' , 2 , 5478 , 'foo' , 8852, , 'Doe' ,2154 , 119 ];
　　items.length; // return 11
　　items.splice(3,1) ;
　　items.length; // return 10
　　/* items 结果为 [12, 548, "a", 5478, "foo", 8852, undefined × 1, "Doe", 2154, 119]

var myArray = [12 , 222 , 1000 , 124 , 98 , 10 ]; 
　　myArray.length = 4; // myArray will be equal to [12 , 222 , 1000 , 124].

myArray.length = 10; // the new array length is 10
myArray[myArray.length - 1] ; // undefined

var foo = 10; 
　　foo == 10 && doSomething(); // is the same thing as if (foo == 10) doSomething();
　　foo == 5 || doSomething(); // is the same thing as if (foo != 5) doSomething();

　　function doSomething(arg1){
arg1 = arg1 || 10; // arg1 will have 10 as a default value if it's not already set
　　}

　　var squares = [1,2,3,4].map(function (val) { 
return val * val; 
　　});
　　// squares will be equal to [1, 4, 9, 16]

var num =2.443242342;
　　num = num.toFixed(4); // num will be equal to 2.4432

　　0.1 + 0.2 === 0.3 // is false
　　9007199254740992 + 1 // is equal to 9007199254740992
　　9007199254740992 + 2 // is equal to 9007199254740994

for (var name in object) { 
　　if (object.hasOwnProperty(name)) {
　　 // do something with name
　　 } 
　　}

var a = 0;
　　var b = ( a++, 99 );
　　console.log(a); // a will be equal to 1
　　console.log(b); // b is equal to 99

　var navright = document.querySelector('#right');
　　var navleft = document.querySelector('#left');
　　var navup = document.querySelector('#up');
　　var navdown = document.querySelector('#down');

　isFinite(0/0) ; // false
　　isFinite("foo"); // false
　　isFinite("10"); // true
　　isFinite(10); // true
　　isFinite(undefined); // false
　　isFinite(); // false
　　isFinite(null); // true，这点当特别注意

　var numbersArray = [1,2,3,4,5];
　　 var from = numbersArray.indexOf("foo") ; // from is equal to -1
　　 numbersArray.splice(from,2); // will return [5]

　var person = {name :'Saad', age : 26, department : {ID : 15, name : "R&D"} };
　　var stringFromPerson = JSON.stringify(person);
　　/* stringFromPerson 结果为 "{"name":"Saad","age":26,"department":{"ID":15,"name":"R&D"}}" */
　　var personFromString = JSON.parse(stringFromPerson);
　　/* personFromString 的值与 person 对象相同 */

　var func1 = new Function(functionCode);
　　var func2 = eval(functionCode);

var func1 = new Function(functionCode);
　　var func2 = eval(functionCode);

　　var sum = 0; 
　　for (var i in arrayNumbers) { 
　　 sum += arrayNumbers[i]; 
　　}

　var sum = 0; 
　　for (var i = 0, len = arrayNumbers.length; i < len; i++) { 
　　 sum += arrayNumbers[i]; 
　　}

for (var i = 0; i < arrayNumbers.length; i++)

setInterval('doSomethingPeriodically()', 1000); 
　　setTimeout('doSomethingAfterFiveSeconds()', 5000);

setInterval(doSomethingPeriodically, 1000); 
　　setTimeout(doSomethingAfterFiveSeconds, 5000);

　function getCategory(age) { 
　　 var category = ""; 
　　 switch (true) { 
　　 case isNaN(age): 
　　 category = "not an age"; 
　　 break; 
　　 case (age >= 50): 
　　 category = "Old"; 
　　 break; 
　　 case (age <= 20): 
　　 category = "Baby"; 
　　 break; 
　　 default: 
　　 category = "Young"; 
　　 break; 
　　}; 
　　 return category; 
　　} 
　　getCategory(5); // 将返回 "Baby"

function clone(object) { 
　　 function OneShotConstructor(){};
　　 OneShotConstructor.prototype = object; 
　　 return new OneShotConstructor();
　　}
　　clone(Array).prototype ; // []

　　function escapeHTML(text) { 
var replacements= {"<": "<", ">": ">","&": "&", "\"": """}; 
return text.replace(/[<>&"]/g, function(character) { 
return replacements[character]; 
　　 });
　　}

var object = ['foo', 'bar'], i; 
for (i = 0, len = object.length; i <len; i++) { 
try { 
// do something that throws an exception
} 
catch (e) { 
// handle exception 
}
}

var object = ['foo', 'bar'], i; 
try {
for (i = 0, len = object.length; i <len; i++) { 
// do something that throws an exception
}
}
catch (e) { 
// handle exception 
}

　var xhr = new XMLHttpRequest ();
　　xhr.onreadystatechange = function () { 
　　 if (this.readyState == 4) { 
　　 clearTimeout(timeout); 
　　 // do something with response data
　　 } 
　　} 
　　var timeout = setTimeout( function () { 
　　 xhr.abort(); // call error callback 
　　}, 60*1000 /* timeout after a minute */ );
　　xhr.open('GET', url, true); 
　　xhr.send();

var timerID = 0;
　　function keepAlive() {
　　 var timeout = 15000; 
　　 if (webSocket.readyState == webSocket.OPEN) { 
　　 webSocket.send(''); 
　　 } 
　　 timerId = setTimeout(keepAlive, timeout); 
　　} 
　　function cancelKeepAlive() { 
　　 if (timerId) { 
　　 cancelTimeout(timerId); 
　　 } 
　　}

　var min = Math.min(a,b);
　　A.push(v);

　var min = a < b ? a : b;
　　A[A.length] = v;