转载：《44个Javascript{{BANNED}}题》

摘要：第题第题第题第题第题第题第题第题第题第题第题第题第题第题第题第题第题第题第题第题第题第题属性是中可表示的最小的数接近，但不是负数。

["1","2","3"].map(parseInt);

[typeof null,null instanceOf Object]

[[3,2,1].reduce(Math.pow),[].reduce(Math.pow)]

var val = "smtg";
console.log("value is" + (val === "smtg") ? "Something" : "Nothing");

var name = "World";
(function(){
    if (typeof name === "undefined") {
        var name = "jack";
        console.log("Goodbye" + name);
    } else {
        console.log("Hello" + name);
    }
})();

var END = Math.pow(2,53);
var START = END - 100;
var count = 0;
for(var i = START; i <= END; i++){
    count++;
}
console.log(count);

var arr = [0,1,2];
arr[10] = 10;
arr.filter(function(x){ return x === undefined});

var two = 0.2;
var one = 0.1;
var eight = 0.8;
var six = 0.6;
[two - one == one, eight - six == two]

function showCase(value){
    switch(value){
        case "A":
            console.log("Case A");
            break;
        case "B":
            console.log("Case B");
            break;
        case undefined:
            console.log("undefined");
            break;
        default:
            console.log("unknown");
            break;
    }
}

showCase(new String("A"))

function showCase(value){
    switch(value){
        case "A":
            console.log("Case A");
            break;
        case "B":
            console.log("Case B");
            break;
        case undefined:
            console.log("undefined");
            break;
        default:
            console.log("unknown");
            break;
    }
}

showCase(String("A"))

function isOdd(num){
    return num % 2 == 1;
}
function isEven(num){
    return num % 2 == 0;
}
function isSane(num){
    return isEven(num) || isOdd(num);
}

var values = [7, 4, "13", -9, Infinity];
values.map(isSane);

Array.isArray(Array.prototype);

var a = [0];
if([0]){
    console.log(a == true);
}else{
    console.log("wut");
}

parseInt(3, 8);
parseInt(3, 2);
parseInt(3, 0);

[] == [];

"5" + 3;
"5" - 3;

1 + - + + + - + 1

var arr = Array(3);
arr[0] = 2;
arr.map(function(item){
    return "1";
});

function sidEffecting(arr){
    arr[0] = arr[2];
}
function bar(a, b, c){
    c = 10;
    sidEffecting(arguments);
    return a + b + c;
}
bar(1,1,1);

var a = 11111111111111000;
var b = 111;
console.log(a + b);

var x = [].reverse;
x();

Number.MIN_VALUE > 0;
// MIN_VALUE 属性是 JavaScript 中可表示的最小的数（接近 0 ，但不是负数）。它的近似值为 5 x 10-324

[1 < 2 < 3, 3 < 2 < 1];

2 == [[[2]]]

3.toString();
3..toString();
3...toString();

(function(){
    var x = y = 1;
})();
x;
y;

var a = /123/;
var b = /123/;
a == b;
a === b;

var a = [1, 2, 3];
var b = [1, 2, 3];
var c = [1, 2, 4];
a == b;
a === b;
a > c;
a < c;

var a = {};
var b = Object.prototype;
[a.prototype === b, Object.getPrototypeOf(a) === b];

function f(){};
var a = f.prototype, b = Object.getPrototypeOf(f);
a === b;

function foo(){}
var oldName = foo.name;
foo.name = "bar";
[oldName, foo.name];

"1 2 3".replace(/d/g,parseInt);

function f(){}
var parent = Object.getPrototypeOf(f);
f.name; //?
parent.name; //?
typeof eval(f.name) //?
typeof eval(parent.name) //?

var lowerCaseOnly = /^[a-z]+$/;
[lowerCaseOnly.test(null), lowerCaseOnly.test()];

[,,,].join(", ");

var a = {class:"Animal", name:"Fido"};
a.class;

var a = new Date("epoch");

var a = Function.length;
var b = new Function().length;
a === b;

var b = Date(0);
var b = new Date(0);
var c = new Date();
[a === b, b === c, a === c]

var min = Math.min(), max = Math.max();
min < max;

function captureOne(re, str){
    var match = re.exec(str);
    return match && match[1];
}
var numRe = /num=(d+)/ig;
var wordRe = /word=(w+)/i;

a1 = captureOne(numRe, "num=1");
a2 = captureOne(wordRe, "word=1");
a3 = captureOne(numRe, "NUM=2");
a4 = captureOne(wordRe, "WORD=2");

[a1 === a2, a3 === a4]

var a= new Date("2014-03-19");
var b =new Date(2014, 03, 19);
[a.getDay() === b.getDay(), a.getMonth() === b.getMonth()]

if("http://xxxgif.com/picture.jpg".match(".gif")){
    "a gif file"
}else{
    "note a git file"
}

function foo(a){
    var a;
    return a;
}
function bar(a){
    var a = "bye";
    return a;
}
[foo("hello"),bar("hello")];

本文仅供分享学习使用
如果您发现侵犯了您的权益，请及时告知本人，以便及时删除该文章。