JavaScript id输出仅显示一秒钟然后消失
[英]JavaScript id output only displays for a second then dissapears
问题描述
I am making a simple JavaScript function where you enter two numbers in a form and then the function determines if the sum of the two numbers is a prime. 
我正在制作一个简单的JavaScript函数，您以一种形式输入两个数字，然后该函数确定两个数字的和是否为质数。 It all works but when the function displays a message with the document.getElementById("demo").innerHTML and 一切正常，但是当函数显示带有document.getElementById（“ demo”）。innerHTML和
它仅在网页上停留一秒钟，然后消失。
I want to make it so the message stays until you click on the button again.
我要这样做，以便消息一直保留到您再次单击该按钮为止。
I have searched this site and other site but have not been able to find anything.
我已经搜索了该站点和其他站点，但是找不到任何东西。
Here is the code: 这是代码：
<!DOCTYPE html> <html> <head> <link href="/prime.css" rel="stylesheet" type="text/css" /> <script> function prime() { // get the values from the form var x= document.forms["frm1"]["x"].value; var y= document.forms["frm1"]["y"].value; //test the values of the form if (x == "null"|| x=="" || isNaN(x)|| y=="null" || y==""|| isNaN(y)){ alert("You must enter two numbers."); exit; } //change variables to number and add them together var number = (parseInt(x)+ parseInt(y)); var a=""; var prime = true; //check to make sure number is not less than one if (number <= 1){ alert("Sorry " +number+ " is not a prime."); prime = false; exit; } //check if number is a prime for (var dividby = 2; dividby <= number / 2; dividby++){ if(number % dividby == 0) prime = false; break; } //send congratulations if(prime==true){ a="congratulations " + number + " is a prime!"; } //send condolences else{ a="Sorry "+number+ " is not a prime."; } document.getElementById("demo").innerHTML=a; } </script> </head> <body id="elem"> <div class="div"></div> <div> <br> <h1>PRIME NUMBERS</h1> <p>Please enter two numbers to be added and see if the result is a prime.</p><br> <form name="frm1" > <input type="text" name="x"> + <input type="text" name="y"> <button onclick="prime()">click me</button> </form> <br> <p id="demo"></p> </div> </body> </html>
3 个解决方案
解决方案1
3 2013-02-24 19:05:40
The problem is that your "click me" button is actually submitting the form, causing the page to reload (since your <form> doesn't have an action attribute, it submits to the same page). 问题是您的“单击我”按钮实际上是在提交表单，从而导致页面重新加载（由于您的<form>没有action属性，因此它将提交到同一页面）。 The <button> tag defaults to type="submit" . <button>标记默认为type="submit" 。 To make it NOT a submit button, you need to change it like this: 要使其不是“提交”按钮，您需要像这样更改它：
<button onclick="prime()" type="button">click me</button>
解决方案2
1 2013-02-24 19:06:32
I just tried the code, and what happens is simple: your form is posted when you click the button. 我只是尝试了代码，然后发生的事情很简单：单击按钮后，表单就会发布。
In the button onClick, write onClick=" return prime();" 在按钮onClick中，编写onClick =“ return prime（）;” and add a 并添加一个
return false;
in your javascript function. 在您的javascript函数中。
解决方案3
0 2013-02-24 19:43:16
In your form tag, just add onsubmit="return false;" 在表单标记中，只需添加onsubmit =“ return false;”。 like this- 像这样-
<form name="frm1" onsubmit="return false;" >
This will prevent your form from being submitted. 这将阻止您提交表单。
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