向事件侦听器添加多个元素

Question

我有一个有两个输入的表单，它将采用两个数字，如下所示。 并根据数学运算符显示每个计算的结果。 如何获取两个输入值并将其添加到 eventListener 以监视值更改并根据每个数学运算符更新结果。

<div class="form">
  <input class="input" id="firstNum" />
  <input class="input" id="secondNum" />
</div>

<div class="grid">
  <div class="grid-item">
   <h3>Addition</h3>
   <p id="addition"></p>
  </div>
  <div class="grid-item">
   <h3>Substraction</h3>
   <p id="substraction"></p>
  </div>
  <div class="grid-item">
   <h3>Multiplication</h3>
   <p id="multiplication"></p>
  </div>
  <div class="grid-item">
   <h3>Division</h3>
   <p id="division"></p>
  </div>
</div>

operator.js 导出每个数学运算符。

export function addition (a, b) { 
    return parseInt(a) + parseInt(b)
}

export function substraction (a, b) { 
    return parseInt(a) - parseInt(b)
}

export function multiplication (a, b) { 
    return parseInt(a) * parseInt(b)
}

export function division (a, b) { 
    return (a / b).toFixed(1)
}

脚本.js

import * as mathOperator from "./operators.js"

document.querySelectorAll(".input")
    .forEach(function (element) { 
        element.addEventListener("change", function (event) {
            let a = event.currentTarget.getAttribute("id")
            let b = event.currentTarget.getAttribute("id")
            console.log(a, b)
            document.getElementById("addition").textContent = mathOperator.addition(a, b)
            document.getElementById("substraction").textContent = mathOperator.substraction(a, b)
            document.getElementById("multiplication").textContent = mathOperator.multiplication(a, b)
            document.getElementById("division").textContent = mathOperator.division(a, b)
        })
    })

Answer 1

只需使用 id 选择值并进行计算。

示例实现。

 function addition(a, b) { return parseInt(a) + parseInt(b) } function substraction(a, b) { return parseInt(a) - parseInt(b) } function multiplication(a, b) { return parseInt(a) * parseInt(b) } function division(a, b) { return b === 0 ? 0 : (a / b).toFixed(1) } function calculate() { const a = document.getElementById("firstNum").value || 0; const b = document.getElementById("secondNum").value || 0; document.getElementById("addition").textContent = addition(a, b) document.getElementById("substraction").textContent = substraction(a, b) document.getElementById("multiplication").textContent = multiplication(a, b) document.getElementById("division").textContent = division(a, b) } document.querySelectorAll(".input") .forEach(function (element) { element.addEventListener("change", function (event) { calculate() }) })

 <div class="form"> <input class="input" id="firstNum" /> <input class="input" id="secondNum" /> </div> <div class="grid"> <div class="grid-item"> <h3>Addition</h3> <p id="addition"></p> </div> <div class="grid-item"> <h3>Substraction</h3> <p id="substraction"></p> </div> <div class="grid-item"> <h3>Multiplication</h3> <p id="multiplication"></p> </div> <div class="grid-item"> <h3>Division</h3> <p id="division"></p> </div> </div>