<script type="text/javascript">
var a=[1,2,3,3,4,5,5,6,8]
var sum=0
a.forEach(i=>sum+=i)
alert(sum)
</script>
//求平方
<script type="text/javascript">
var a=[1,2,3,3,4,5,5,6,8]
var sum=0
a.forEach(i=>sum+=i*i)
alert(sum)
</script>
<script type="text/javascript">
var a=[1,2,3,3,4,5,5,6,8]
var sum=0
var c=a.map(function(i){
return (2*i+1)
})
c.forEach(i=>sum+=i)
alert(sum)
</script>
<script type="text/javascript">
var a=[1,2,3,3,4,5,5,6,8]
var sum=0
a.forEach(i=>sum+=2*i+1)
alert(sum)
</script>
