How do I add something to my html using javascript without erasing the whole page

问题

I have a small calculator that I'm adding to my html. It has a few dropdowns to select stuff and when a person hits a submit button, I'd like to display a picture below the calculator in my html. I've tried using a javascript function with: document.write() but that clears the whole page. Is there a way that I can get a javascript function to run which only adds a picture to my page when a submit button is clicked?

Here's a BASIC outline of my code with the part I'm having trouble with:

<html>

<head>
<script type="text/javascript">

function calc_rate() {

    //code that displays a message after the submit button is hit        
    document.write("answer");
}

</script>

</head>
<body>


<table>


<tr>
    <td class=rate_calc_label>Select Your Option Type:</td>
<td><select name="type1">
    <option></option>
    <option>1</option>
    <option>2</option>
    <option>3</option>
    </select></td>
</tr>  


<tr>
<td class=rate_calc_label>Select The Second Number:</td>
<td><select name="type2">
    <option>1</option>
    <option>2</option>
    <option>3</option>
    <option>4</option>
    <option>5</option>
    <option>6</option>
    <option>7</option>
    <option>8</option>
    <option>9</option>
    <option>9</option>
    <option>10</option>
    <option>11</option>
    <option>12</option>
    </select></td>
</tr>


<tr>
<td><input type="submit" value="Submit" name="calc_button" onclick="calc_rate()"/></td>
<td></td>
</tr>    

</table>

</body>
</html>

would it be possible to use some kind of inner-HTML? That's what I got from others on stockoverflow but I'm still a little confused

回答1:

You need a placeholder element for your output. Then set the innerHTML for that element:

<div id='answer'></div>

then:

document.getElementById('answer').innerHTML = "answer is:" + yourdata

回答2:

Don't use document.write, period. Use DOM operations: http://www.quirksmode.org/dom/intro.html

回答3:

Instead of document.write() you can set the innerHTML property of any DOM node to add text to the page.

Say you add a <div id='result'></div> to the end of the page (before the body tag). Then in your javascript have:

var result_display = document.getElementById('result');
// and in calc_rate():
result_display.innerHTML = "answer";

Note that this will always reset the result_display's text. You can also wrap that operation in a function:

function displayResult(result){
    result_display.innerHTML = '<h2>' + result + '</h2>'; // or whatever formatting
}

来源：https://stackoverflow.com/questions/11907053/how-do-i-add-something-to-my-html-using-javascript-without-erasing-the-whole-pag

标签

javascript

html

document.write