Question

我无法验证JavaScript的两个条件。当我输入一个数字时，第一个if语句将起作用。但是，else if语句不会打印出符合该条件的任何内容。一些帮助将不胜感激。

<html>
<head>

<script>
function return() {
  var num1 = document.getElementById("num1");
  var num2 = document.getElementById("num2");
  var x = num1.value;
  var y = num2.value
  if (isNaN(x)) {
    alert("Please only enter numbers");
    return false;
  }
  if (isNaN(y)) {
    alert("Please only enter numbers");
    return false;
  }
  var calculation = (x + y) / (x * y);
  var result = document.getElementById("answer");
  if (calculation > 1) {
    result.value = "Your number is more than 1";
  } else {
    if (calculation <= 0.5) {
      result.value = "Your number is 1 or less";
    }
  }
}
  </script>
  </head>

  <body>
   1: <input type="text" id="num1"/>
   2: <input type="text" id="num2"/>
  <input type="button" value="Calculate" onclick= "return()"/>
  <input type="text" id="answer"/>
</body>
</html>

Answer 1

您不能将保留字用作函数名，变量名或标签。

同时将输入值转换为Number，可以使用Unary plus。

<小时/> InputElement.value返回String类型的值，因此，如果值为2和3，则计算结果为("2" + "3" ==> "23")，值将连接，不会添加！

另请注意，您的遗失条件未得到处理，您还应该有其他条件。

function calculate() {
  var num1 = document.getElementById("num1");
  var num2 = document.getElementById("num2");
  var x = num1.value;
  var y = num2.value
  if (isNaN(x)) {
    alert("Please only enter numbers");
    return false;
  }
  if (isNaN(y)) {
    alert("Please only enter numbers");
    return false;
  }
  var calculation = (+x + +y) / (x * y);
  var result = document.getElementById("answer");
  if (calculation > 1) {
    result.value = "Your number is more than 1";
  } else {
    if (calculation <= 0.50) {
      result.value = "Your number is 1 or less";
    } else {
      result.value = "Unhandled condition!";
    }
  }
}

1: <input type="text" id="num1" /> 2: <input type="text" id="num2" />
<input type="button" value="Calculate" onclick="calculate()" />
<input type="text" id="answer" />

Answer 2

return is statement，不要将它用作函数名。

    <!doctype html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Document</title>
    </head>
    <body>
        1: <input type="text" id="num1"/>
       2: <input type="text" id="num2"/>
      <input type="button" value="Calculate" onclick= "returnq()"/>
      <input type="text" id="answer"/>
    <script>

    function returnq(){
      var num1 = document.getElementById("num1");
      var num2 = document.getElementById("num2");
      var x = num1.value;
      var y = num2.value
      if (isNaN(x)){
      alert("Please only enter numbers");
      return false;
      }
      if (isNaN(y)){
      alert("Please only enter numbers");
      return false;
      }
      var calculation = (x+y)/(x*y);
      var result = document.getElementById("answer");
      if (calculation > 1) {
      result.value = "Your number is more than 1";
      }
      else {
      if (calculation <= 0.50) {
        result.value = "Your number is 1 or less";
       }
      }
     }


    </script>
    </body>
    </html>

没问题......

抱歉两个答案同时

Answer 3

else声明错误尝试删除if (calculation <= 0.50)，如下所示：

    else {   
    result.value = "Your number is 1 or less";       
    }

Answer 4

问题是你return迫使函数退出，永远不会让第二个if块有机会运行。此外，return是JavaScript中的保留关键字，不建议用作函数名称。 Link to jsbin

这里有一些可行的代码：

  1:<input type="text" id="num1" /> <br />
    2:<input type="text" id="num2" /> <br />
  <input type="button" value="Calculate" onclick="sumUpper()" />
  <input type="text" id="answer" />

 function sumUpper() {
   var num1 = document.getElementById("num1");
   var num2 = document.getElementById("num2");
   var x = parseFloat(num1.value);
     var y = parseFloat(num2.value);
     var xError = false;
     var yError = false;

   if (isNaN(x)) {
     console.log("Please only enter numbers x");
     xError = true;
   }
   if (isNaN(y)) {
     console.log("Please only enter numbers y");
     var yError = true;
   }
     console.log(xError, yError);
   var calculation = (x + y) / (x * y);
   var result = document.getElementById("answer");
   if (calculation > 1) {
     result.value = "Your number is more than 1";
   } else {
     if (calculation <= 0.50) {
       result.value = "Your number is 1 or less";
     }
   }
 }

Answer 5

我猜这些数字正在四舍五入，将1和0.5都显示为1.如果必须使用else，请尝试一个限制估算的数学函数。

Answer 6

您无法使用功能名称return。 return是javascript关键字。

尝试这样的事情。

＆＃13;

function myFunction(){
	 var num1 = document.getElementById("num1");
		  var num2 = document.getElementById("num2");
		  var x = num1.value;
		  var y = num2.value;
		  
		  if (isNaN(x)){
		  	alert("Please only enter numbers");
		  	return false;
		  }
		  if (isNaN(y)){
		  	alert("Please only enter numbers");
		  	return false;
		  }
		  var calculation = (x+y)/(x*y);
		  var result = document.getElementById("answer");
		  if (calculation > 1) {
		  	result.value = "Your number is more than 1";
		  } else {
		  	if (calculation <= 0.50) {
		    	result.value = "Your number is 1 or less";
		  	}
		  }
		}

＆＃13;

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
1: <input type="text" id="num1"/>
2: <input type="text" id="num2"/>
<input type="button" value="Calculate" onclick= "myFunction()"/>
<input type="text" id="answer"/>

＆＃13;

如果......否则如果比较两种不同条件的数字的声明

6 个答案: