从对象获取数组的特定值并求和

Question

我有以下代码：

   if (this.places.length) {
    console.log(this.places);
    var myData = this.places.map(({ points }) => points);
    var myTotal = 0;  // Variable to hold your total

    for(var i = 0, len = myData.length; i < len; i++) {
        myTotal += myData[i][1];  // Iterate over your first array and then grab the second element add the values up
    }
    console.log(myTotal);
  }

我有一个对象 ，我需要从该对象中提取所有数组，并从该数组中仅提取一个特定值，例如点。

主要目标是将所有点求和并保存到一个新变量中。上面的代码不起作用。

Answer 1

如果我理解正确，您想计算数组points中包含的每个Place对象中所有字段的总数，this.places并将结果存储在新变量中myTotal-一种实现方法是通过reduce()：

if (this.places.length) {

    /* The total returned by reduce() will be stored in myTotal */
    let myTotal = this.places.reduce((total, place) => {    

        /* For each place iterated, access the points field of the 
        current place being iterated and add that to the current
        running total */
        return total + place.points;

    }, 0); /* Total is initally zero */

    console.log(this.places);
    console.log(myTotal);
}