es6学习重点

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数组的扩展

数组合并：[...arr1,...arr2,...arr3]

字符串转字符数组：[..."hello"]--------------["h","e","l","l","o"]

for...of遍历数组的键、值、以及各项键值对信息

for (let index of ['a', 'b'].keys()) {
    console.log(index);
}
// 0
// 1

for (let elem of ['a', 'b'].values()) {
    console.log(elem);
}
// 'a'
// 'b'

for (let [index, elem] of ['a', 'b'].entries()) {
    console.log(index, elem);
}
// 0 "a"
// 1 "b"

对象的拓展

var firstname='jack';
var man = {
    firstname,
    say(something){
        console.log(this.firstname);
        console.log("hello "+something);
    }
};
man.say('world');

class与继承

class Point {
    constructor(x, y) {
        this.x = x;
        this.y = y;
    }

    toString() {
        return '(' + this.x + ', ' + this.y + ')';
    }
}

class ColorPoint extends Point {
  constructor(x, y, color) {
    super(x, y);                                // 调用父类的constructor(x, y)
    this.color = color;
  }

  toString() {
    return this.color + ' ' + super.toString(); // 调用父类的toString()
  }
}

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