令人眼前一亮的数组求和方式

<script>
    var arr = [10,20,30];
    var num = 0;
    for (var i = 0; i < arr.length; i++) {
        num += arr[i]
    }
    console.log(‘for循环的结果=‘ + num)

    var num1 = 0;
    arr.forEach((item,index) => {
        num1 += item
    })
    console.log(‘forEach的结果=‘ + num1)

    var num2 = 0;
    arr.map((item,index) =>{
        num2 += item
    })
    console.log(‘map的结果=‘+ num2)

    var num3 = 0;
    arr.filter((item,index) =>{
        num3 += item
    })
    console.log(‘filter的结果=‘+ num3)

    var num4 = 0;
    arr.some((item,index) =>{
        num4 += item
    })
    console.log(‘some的结果=‘+ num4)

    var num5 = 0;
    arr.every((item,index) =>{
       return num5 += item
    })
    console.log(‘severy的结果=‘+ num5)
</script>

    var num6 = arr.reduce((num,item) => {
        console.log(num + ‘---‘ + item)
        return num + item
    },0)
    console.log(num6)