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<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
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<title>Document</title>
<script>
// What you have
var officers = [
{id:1,name:'andy',age:15,weight:60},
{id:2,name:'sam',age:20,weight:50},
{id:3,name:'julia',age:15,weight:40},
{id:4,name:'tom',age:25,weight:30}
]
// What you need
// [1,2,3,4]
// forEach()
// var officersIds = [];
// officers.forEach(val => {
// console.log(val)
// officersIds.push(val.id)
// })
// console.log(officersIds)
// map
const officersIds = officers.map(val=>val.id)
// console.log(officersIds)
// filter
const teenager = officers.filter(officers => officers.age < 18)
console.log(teenager)
// {id: 1, name: "andy", age: 15, weight: 60}
// {id: 3, name: "julia", age: 15, weight: 40}
const adult = officers.filter(officers => officers.age > 18)
console.log(adult)
// {id: 2, name: "sam", age: 20, weight: 50}
// {id: 4, name: "tom", age: 25, weight: 30}
// reduce 可以直观的返回数组里面指定的一个值或者对象
// 所有职员的体重
const totalWeight = officers.reduce((param1,param2) => param1+param2.weight,0)
console.log(totalWeight) //180
</script>
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.map() .filter() .reduce() 的用法
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转载自www.cnblogs.com/andyZhang0511/p/12035316.html
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