ES6的内置对象扩展实现示例_javascript技巧_

let ary = [1,2,3]; ...ary //1,2,3 console.log(...ary); //1 2 3 //console.log方法可以接收以","分隔的参数，一次输出多个内容 //为啥输出的结果没有逗号了，因为参数序列里的逗号被console.log当成参数分隔符了

//方法一 let ary1 = [1,2,3]; let ary2 = [4,5,6]; let ary3 = [...ary1,...ary2]; console.log(ary3); //[1,2,3,4,5,6]

//方法二 ary1.push(...ary2);

 let ary1 = [1, 2, 3]; let ary2 = [4, 5, 6]; ary2.push(...ary1); console.log(ary2); //[4,5,6,1,2,3]

let oDivs = document.getElementByTagName('div'); oDivs = [...oDivs];

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let arrayLike = { '0': 'a', '1'：'b', '2': 'c', length: 3 //必须要有这一句 }; console.log(arrayLike); let arr2 = Array.from(arrayLike); // ['a','b','c'] console.log(arr2);

let arrayLike = { "0":1, "1":2, "length":2 } let newAry = Array.from(arrLike,item=> item*2);

var arrayLike = { "0": "1", "1": "2", "length": 2 } var ary = Array.from(arrayLike, item => item * 2) //数组里有多少元素 这一句就执行多少次 console.log(ary) //[2,4]

let ary = [{ id :1, name:'张三' },{ id:2, name:'李四' } ]; let target = ary.find((item,index) => item.id==2 )

let ary = [1, 5, 10, 15]; let index = ary.findIndex((value,index) => value>9); console.log(index); //2

[1,2,3].includes(2); //true [1,2,3].includes(4); //false