es67 

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<head>
<meta charset="UTF-8">
<title>对应位置</title>
<script src="../../../vendor/traceur.js"></script>
<script src="../../../vendor/bootstrap.js"></script>
<script type="text/traceur">
//   ES6允许按照一定模式，从数组和对象中提取值，对变量进行赋值，这被称为解构（Destructuring） 。
    // ES5
    var a = 1;
    var b = 2;
    var c = 3;

    // ES6
    var [a, b, c] = [1, 2, 3];
    console.log(a);    //1
    console.log(b);    //2
    console.log(c);    //3

--------------------------------------------------------
    let [foo, [[bar], base]] = [1, [[2], 3]];
    console.log(foo);    //1
    console.log(bar);    //2
    console.log(base);    //3

    let [, , third] = ["first", "second", "third"];
    console.log(third);    //third

    let [one, , three] = ["One", "Two", "Three"];
    console.log(one);    //One
    console.log(three);    //Three

    let [head, ...tail] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
    console.log(head);    //0
    console.log(tail);    //[1, 2, 3, 4, 5, 6, 7, 8, 9]
    
    
    let [head, tail] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
    console.log(head);    //0
    console.log(tail);    //1
----------------------------------------------------    
    var [temp] = [];
    console.log(temp);    //undefined
    var [first, second] = [100];
    console.log(first);    //100
    console.log(second);//undefined

----------------------------------------------------    
    
    let [x, y] = [1, 2, 3];
    console.log(x);    //1
    console.log(y);    //2

    let [a, [b], c] = [1, [2, 3], 4];
    console.log(a);    //1
    console.log(b);    //2
    console.log(c);    //4
    
-----------------------------------------------
    var [temp = "string"] = [];
    console.log(temp);    //string，没有值走默认

    var [temp = "string"] = ["tempString"];
    console.log(temp);    //tempString，默认值和指定值冲突（指定值不为未定义）用指定值、指定值为未定义用默认值，

    var [x = "aaa", y] = ["bbb"];
    console.log(x);    //bbb
    console.log(y);    //undefined

    var [m, n = "aaa"] = ["bbb"];
    console.log(m);    //bbb
    console.log(n);    //aaa

    var [p, q = "aaa"] = ["bbb", undefined];
    console.log(p);    //bbb
    console.log(q);    //aaa

-------------------------------------------------------    
    var [temp] = 1;            //正确写法:var [temp] = [1];  报错1[Symbol.iterator] is not a function at eval
    var [temp] = false;        //报错:false[Symbol.iterator] is not a function at eval
    var [temp] = NaN;        //报错:NaN[Symbol.iterator] is not a function at eval
    var [temp] = undefined; //报错:Cannot read property 'Symbol(Symbol.iterator)' of undefined at eval
    var [temp] = null;        //报错:Cannot read property 'Symbol(Symbol.iterator)' of null at eval
-------------------------------------------------------

</script>
</head>
<body>

</body>
</html>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Iterator接口</title>
<script src="../../../vendor/traceur.js"></script>
<script src="../../../vendor/bootstrap.js"></script>
<script type="text/traceur">
//只要某种数据结构具有Iterator接口，都可以采用数组形式的解构赋值。
    let [a, b, c] = new Set(["a", "b", "c"]);
    console.log(a);    //a
    console.log(b);    //b
    console.log(c);    //c

    function* fibs() {
        let a = 0;
        let b = 1;
        while (true) {
            yield a;
            [a, b] = [b, a + b];
        }
    };
    var [first, second, third, fourth, fifth, sixth] = fibs();
    console.log(sixth);    //5
</script>
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<body>

</body>
</html>

 

posted @ 2017-06-09 00:05  无天666  阅读(872)  评论(0)    收藏  举报