Question

例如-显示从5（4 * 5）开始到9结束的4次表。

- 4*5 = 20
- 4*6 = 24
- 4*7 = 28
- 4*8 = 32
- 4*9 = 36

我很困惑如何添加开始和结束值。

function printTable(){

    var timesTable =Number(document.getElementById('txtNumber').value);
    for(var i=1; i<=10; i++){
    var pTag= document.getElementById('pPrint');
    pTag.innerHTML += (timesTable*i) + "<br/>"
    }
}

<body style="text-align: center;">
    <h1>JavaScript - Function to Display Table of an entered Number.</h1>
    <p><input type="text" id="txtNumber" placeholder="Enter number"/></p>
    <h1>enter the start value</h1>
    <p><input type="text" id="textNumber" placeholder="Enter number"/></p>
    <h1>enter the end value</h1>
    <p><input type="text" id="teextNumber" placeholder="Enter number"/></p>
    <p><input type="button" value="Print Table." onclick='printTable()'/>
    <!--print numbers-->
    <p id="pPrint"></p>
</body>

如何在javascript中为乘法时间表添加起点和终点？

Answer 1

如果我正确理解了您的问题，也许您可以执行以下操作；

通过Number(document.getElementById('textNumber').value)
通过Number(document.getElementById('teextNumber').value)
使用您的for循环通过for(var i= start; i<= end; i++){开始从起始编号到结束编号的循环播放

您还应该检查起始编号是否小于结束编号，以确保循环终止：

function printTable(){
  
  var start = Number(document.getElementById('textNumber').value);
  var end = Number(document.getElementById('teextNumber').value);
  var timesTable =Number(document.getElementById('txtNumber').value);

  // Query document for pTag once, rather than per loop iteration
  var pTag= document.getElementById('pPrint');
  
  // Check that start is less than end, to ensure that the loop 
  // terminates (ie doesn't loop infinitely)
  if(start < end) {
  
    for(var i= start; i<= end; i++){
       
      // Present the multiplication in the required format 
      pTag.innerHTML += ('- ' + i + ' * ' + timesTable + ' = ' + (timesTable*i) + '<br/>')
    }
  }
  
}

<h5>JavaScript - Function to Display Table of an entered Number.</h5>
<p><input type="text" id="txtNumber" placeholder="Enter number"/></p>
<h5>enter the start value</h5>
<p><input type="text" id="textNumber" placeholder="Enter number"/></p>
<h5>enter the end value</h5>
<p><input type="text" id="teextNumber" placeholder="Enter number"/></p>
<p><input type="button" value="Print Table." onclick='printTable()'/>

<p id="pPrint"></p>

Answer 2

如果我正确理解了您的问题，那么我将添加乘法函数，如下所示：

function printTable(){

    var ps =Number(document.getElementById('txtNumber').value);
    var start =Number(document.getElementById('textNumber').value);
    var end =Number(document.getElementById('teextNumber').value);
    for(var i=start; i<=end; i++){
    var pTag= document.getElementById('pPrint');
    pTag.innerHTML += "- " + (ps) + "*" + (i) + " = " + ps*i + "<br/>"
    }
}

<body style="text-align: center;">
    <h1>JavaScript - Function to Display Table of an entered Number.</h1>
    <p><input type="text" id="txtNumber" placeholder="Enter number"/></p>
    <h1>enter the start value</h1>
    <p><input type="text" id="textNumber" placeholder="Enter number"/></p>
    <h1>enter the end value</h1>
    <p><input type="text" id="teextNumber" placeholder="Enter number"/></p>
    <p><input type="button" value="Print Table." onclick='printTable()'/>
    <!--print numbers-->
    <p id="pPrint"></p>
</body>

ps是开始的乘法数，start是开始的倍数，结束是结束数。

编辑：添加缺少的框

Answer 3

将for循环的起点和终点添加如下：

function printTable(){
    var timesTable =Number(document.getElementById('txtNumber').value);
    var start = document.getElementById("textNumber").value;
    var end = document.getElementById("teextNumber").value;

    for(var i=start; i<=end; i++){
    var pTag= document.getElementById('pPrint');
    pTag.innerHTML += (timesTable*i) + "<br/>"
 }

}

在JavaScript中为乘法时间表添加起点和终点

3 个答案: