Question

我真的很困惑如何解决这个问题：

我有一个像这样的数组：

arr=["X12","Z1","Y7","Z22","X4","X8"]

我希望对以下元素执行数学功能：

每个以“ X”开头的元素将具有固定值5，因此，如果数组3中有arr个以“ X”开头的元素，则应为： (fixed value of X) multiplied by (No. of "X" element occurrences inside array) = 5x3 = 15.

我尝试过类似的方法来计算编号。出现了“ X”元素，但它不起作用。

var xcounter = 0;
calculate(){
          this.arr.forEach(element => {
            if(this.arr.includes("X"))
            {
              this.xcounter++; //this doesn't give me no. of X element occurrences though.
            }
          });
        }

什么是无杂乱的方式做到这一点的？

Answer 1

您可以尝试将数组filter()与字符串startsWith()方法一起使用。

var arr = ["X12","Z1","Y7","Z22","X4","X8"];
var valueX = 5;

var occurencesX = arr.filter(item => item.startsWith('X')).length;

console.log(occurencesX * valueX);

Answer 2

您也可以尝试

循环到您的数组
查找您发现有多少次以X开头的值

var  arr=["X12","Z1","Y7","Z22","X4","X8"]
let total = 0
arr.forEach(
  (row) =>{
        total =  row.startsWith('X')? total + 1 : total
  }
)

console.log(total * 5)

带打字稿数组的数学-Angular

2 个答案: