JS_关键字详细

break

for(var i=0;i<10;i++){
    if(i==3) break;
    console.log(i)　　//1,2,3
}

switch , case

function main(arg){
    switch(arg){
        case 1:
            console.log(1);
            break;
        case 2:
            console.log(2);
            break;
        case 3:
            console.log(3);
            break;
    }
}
main(3);　　//3

 

try , catch

try{
    console.log(main)
}catch(e){
    console.log(e)　　//main is not defined
}

continue

for(var i=0;i<5;i++){
    if(i==2) continue;
    console.log(i)　　//0,1,3,4
}

default

function main(arg){
    switch(arg){
        case 1:
            console.log(1);
            break;
        case 2:
            console.log(2);
            break;
        case 3:
            console.log(3);
            break;
        default:
            console.log(null)
    }
}
main(4);　　//null

delete

var person = {
    name:"sao",
    age:"18"
}
console.log(person.name);　　//sao
delete person.name;
console.log(person.name);　　//undefined

do while , while

var num = 6;
do{
    console.log(num);　　//6
    num++
}
while(num<5);
/*----------------------*/
var num = 3;
while(num<5){
    console.log(num);　　//3,4
    num++
};

if else

var i = 0
if(i==0){
    console.log(true)　　//true
}

finally

try{
    console.log(main)
}catch(e){
    console.log(e)　　//main is not defined
}finally{
    console.log("finally")　　//finally
}

for in

var person = {
    name:"sao",
    age:"18"
}
for(var i in person){
    console.log(i)　　//name,age
}

void , function

void function(){
    console.log("hello")　　//hello
}()

var , new

var name = new String("sao");
console.log(name)　　//sao

return

function main(){
    return console.log("hello")
}
main();

throw , typeof

try{
    throw null
    console.log(main)
}catch(e){
    console.log(typeof e)　　//object
}

this

function main(){
    console.log(this)
}
main.call(new String("sao"));

with

var person = {
    name:"sao",
    age:"18"
}
with(person){
    console.log(name)
}

instanceof

var main = new String("sao");
console.log(typeof main);
console.log(main instanceof String);

PS:

void function(){
    try{
        var main = new Object();
        main.name = "sao";
        main.age = new Number("18");
        do{
            with(main){
                if(age == 18 && age instanceof Number){
                    throw 0;
                }else{
                    throw 1;
                }
            }
        }while(main.age != 18)
    }catch(e){
        switch(e){
            case 0:
                for(var i in main){
                    if(typeof main[i]=="string"){
                        delete main.name
                        continue;
                    }
                }
                break;
            case 1:
                break;
            default:
        }
    }finally{
        (function(){
            alert(this.age)　　//18
        }).call(main)
        return;
    }
}()