在 JavaScript 中使用提示填充数组并使用 push 方法

问题描述

我正在 JavaScript 中学习数组，我正在使用 foreach 和 push 方法。

以下代码按预期工作：

    let numbers = [-1,-2,-3,5,6,1]
    let pos = []
    let neg = []
    
    numbers.forEach(number => {
            if (number<0) {
            neg.push(number)
        } else {
            pos.push(number)
        }
        
        })
        
       document.write("Number of positive numbers are: "+pos + "<br>" + "<br>")
       document.write("Number of negative numbers are: "+neg)

但我想用提示复制这个，而不是对数组中的值进行硬编码。并以 0 结束提示。 我尝试的代码如下，但从来没有评估变量 pos 和 neg'，这是我的代码：

    let numbers = []
    let pos = []
    let neg = []

    let number = parseInt(prompt("Input nr"))
    document.write("Your input nr was: " + number + "<br>" + "<br>")
    
    while (number != 0) {

        number = parseInt(prompt("Input nr"))
        document.write("Your input nr was: " + number + "<br>" + "<br>")

        numbers.forEach(number => {
            if (number<0) {
            neg.push(number)
        } else {
            pos.push(number)
        }
        
        })

    }

    document.write("Number of positive numbers are: "+pos + "<br>" + "<br>")
    document.write("Number of negative numbers are: "+neg)

我在代码中做错了什么？

解决方法

您需要将数字推入数字数组

numbers.push(number)

let numbers = []
    let pos = []
    let neg = []

    let number = parseInt(prompt("Input nr"))
    numbers.push(number)
    document.write("Your input nr was: " + number + "<br>" + "<br>")
    while (number != 0) {

        number = parseInt(prompt("Input nr"))
        numbers.push(number)
        document.write("Your input nr was: " + number + "<br>" + "<br>")
    }
    numbers.forEach(number => {
            if (number<0) {
            neg.push(number)
        } else {
            pos.push(number)
        }
        
    })

    document.write("Number of positive numbers are: "+pos + "<br>" + "<br>")
    document.write("Number of negative numbers are: "+neg)

,

您应该使用 push 方法将其推送到 numbers 数组中：

while (true) {
    let number = parseInt(prompt("Input number"))
    // end on zero
    if (number == 0) {
        break
    }
    // invalid number check
    if (isNaN(number)) {
        alert("Invalid number,try again.");
        continue;
    }
    document.write("Your input nr was: " + number + "<br>" + "<br>")
    // push it to the array
    numbers.push(number)
}
// forEach afterwards
numbers.forEach(number => { /* ... */ })

,

您可以将代码更改为以下

let numbers = []
    let pos = []
    let neg = [];
let number;
   // let number = parseInt(prompt("Input nr"))
    //document.write("Your input nr was: " + number + "<br>" + "<br>")
    
    while (number != 0) {

        number = parseInt(prompt("Input nr"))
        document.write("Your input nr was: " + number + "<br>" + "<br>");
        
        //-----------------------//-
          if(number >0){
            pos.push(number);
          }else if(number < 0){
            neg.push(number);
          }
      //-----------------------//-


    }

    document.write("Number of positive numbers are: "+pos + "<br>" + "<br>")
    document.write("Number of negative numbers are: "+neg)