// 在设计Javascript时,很明显遗漏了数组复制功能。而在ES5中，开发者使用concat()来克隆数组var colors = ["red", "blue", "pink"];var cloneColors = colors.concat();console.log(cloneColors); // ["red", "blue", "pink"]console.log(Object.is(colors, cloneColors)); // false// concat()方法设计初衷是连接两个数组，如果调用时不传递参数则返回当前数组的副本var colors2 = ["black", "green"];console.log(colors.concat(colors2)); // ["red", "blue", "pink", "black", "green"]// ES6 克隆数组let [...cloneArray] = colors;console.log(cloneColors) // ["red", "blue", "pink"]// 可以混合使用对象解构和数组解构来创建更多的复杂的表达式// 6.混合解构let node = {type: "json",age: 1,loc: {start: {line: "solid",column: 20},end: {line: "double",column: 21},range: [0, 3]}};let {loc: {range: [startIndex]}} = node;console.log(startIndex); // 0let {loc: {start},loc: {range: [index]}} = node;console.log(start.line); // solidconsole.log(index); // 0// 7.解构参数function setCookie(name, value, options){options = options || {};let secure = options.secure,path = options.path,domain = options.domain,expires = options.expires;// 设置cookie代码}// name,value是必须的, 函数的声明部分，无法辨识函数的预期函数，必须通过阅读函数体才可以确定具体参数的情况setCookie("type","js", {secure: true,expires: 700});/*function setName(name,options) {let {secure,path,domain,expires} = options;console.log(name);}// Cannot destructure property `secure` of 'undefined' or 'null'// 如果解构函数赋值表达式的右值为null和undefined，则程序会报错setName("zhangsan",null);setName("zhangsan");*/// 8.解构参数的默认值const defaultParam = {secure : false,path : "/",domain : "example.com",expires : new Date(Date.now() + 360000000)}function setName(name,{secure = defaultParam.secure,path = defaultParam.path,domain = defaultParam.domain,expires = defaultParam.expires} = defaultParam) {console.log(name);console.log(expires);}setName("admin"); // admin// Mon Jun 24 2019 22:03:22 GMT+0800 (中国标准时间)