es6,es5的遍历合集

var obj = [{ foo: 'bar', baz: 42 }, { foo: 'bar2', baz: 142 }];

forEach

obj.forEach((item, index) => {
    console.log(item) //{foo: "bar", baz: 42} ...
    console.log(index) //0 ...
  })

for in

  for (const key in obj) {
    console.log(obj[key]) //{ foo: 'bar', baz: 42 } ...
    console.log(key) // 0 ...
  }

for of最适合遍历的是map对象,set对象

  var maps = new Map()
  maps.set("key1", { name: "唐三", value: 123 })
  maps.set("key2", { name: "番茄", value: 456 })
  for (const [key, value] of maps) {
    console.log(key) //key1 ...
    console.log(value) // { name: "唐三", value: 123 } ...
    maps.delete('key1')
  }
  console.log(maps)

使用for of还需要记住3个Object的方法

Object.keys(),Object.values(),Object.entries()
Object.keys(),Object.values(),Object.entries()

  let { keys, values, entries } = Object;
  var obj = [{ foo: 'bar', baz: 42 }, { foo: 'bar2', baz: 142 }];
  for (let key of keys(obj)) {
    console.log(key)
  }
  for (let key of Object.values(obj)) {
    console.log(key)
  }
  for (let key of entries(obj)) {
    console.log(key)
  }

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转载自www.cnblogs.com/lsc-boke/p/11244339.html