给定一个数组[1,2,3,4],如何求其元素的和?(在这种情况下,总数为10。)

我认为每个美元可能有用,但我不确定如何实现它。


当前回答

//Try this way

const arr = [10,10,20,60]; 
const sumOfArr = (a) =>{
    let sum=0;
    for(let i in a) { 
        sum += a[i];
    }
    return sum;
}
console.log(sumOfArr(arr))

其他回答

    <!DOCTYPE html>
    <html>
    <body>

      <p>Click the button to join two arrays.</p>
      <button onclick="myFunction()">Try it</button>
      <p id="demo"></p>
    <script>
var hege = [1, 2,4,6,7,8,8];
var stale = [1, 2,4,5];
function myFunction() {
    console.log((hege.length > stale.length))    
    var children  = (hege.length > stale.length)? abc1() :abc2();       document.getElementById("demo").innerHTML = children;
}
function abc1(){
    console.log(hege,"Abc1")    
    var abcd=hege.map(function (num, idx) {
        console.log(hege.length , idx)
        return stale.length>idx?num + stale[idx]:num;
    })
    return abcd;
}

function abc2(){

    console.log(hege,"Abc2",stale)    
    var abcd=stale.map(function (num, idx) {
        console.log(hege.length , idx)
        return hege.length>idx?num + hege[idx]:num;
    })
    return abcd;
}
</script>

</body>
</html>

为什么不减少?这通常有点反直觉,但使用它求和非常简单:

var a = [1,2,3];
var sum = a.reduce(function(a, b) { return a + b; }, 0);

此外,对于简单数组,使用es6求和。

const sum = [1, 2, 3].reduce((partial_sum, a) => partial_sum + a,0);
 
console.log(sum); 

对于具有默认初始化值的对象数组

const totalAmount = obj => 
    Object.values(obj).reduce((acc, { order_qty, mrp_price }) => 
    acc + order_qty * mrp_price, 0);
    
    console.log(totalAmount); 
var arr = [1, 2, 3, 4];
var total = 0;
for (var i in arr) {
  total += arr[i];
}

使用reduce

设arr=[1,2,3,4];设和=arr.reduce((v,i)=>(v+i));console.log(总和);