SOURCE

const newnums=[10,20,30,50,90,70];
let new1nums=newnums.filter(function(n){return n<=30})
let new2nums=newnums.map(function(n){return n*2});
let new3nums=newnums.reduce(function(prebalue,n){
return prebalue+n
},0)

let newnum1=newnums.filter(function(n){return n<=30}).map(function(n){return n*2}).reduce(function(prebalue,n){
return prebalue+n
},0)
let newnum=newnums.filter(n => n <=30).map(n => n * 2).reduce((pre,n) => pre + n)


console.log(newnum1);
console.log(newnum);

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<div id="app" style="max-width:800px;height:400px">	
	<h2>高级函数</h2>

</div>