摘要：创建数组 let arr = []; let arr = new Array(1,2,5); let arr = Array.from([1,2,3],item=>item+2); //[3,4,5] let arr = arr1.concat(arr2,arr3); //返回新数组，concat 阅读全文

摘要：创建对象let obj = {}; let obj = new Object(); let obj = Object.create(null); //不能不传值，null表示空值 let obj = Object.assign(obj1, obj2, obj3); // **操作obj1对象。** 阅读全文