将宽度从百分比转换为像素

Question

I have a table inside a <div> :

<div id="fixeddiv">
    <table id="fixedtable">
        <tr class="firstrow">
            <td class="td11"></td>
            <td class="td12"></td>
            <td class="td13"></td>
        </tr>

        <tr class="secondrow">
            <td class="td21" style="width:10%"></td>
            <td class="td22" style="width:20%"></td> 
            <td class="td23" style="width:70%"></td>
        </tr>
    </table>
</div>

CSS:

#fixeddiv
{
    overflow:auto;
    margin:0px;
    padding:0px;
    position: relative;
    text-align:left;
    width: 48%;
}

#fixedtable
{
    background-color: White;
    border-spacing:0px;
    cursor: pointer;
    width: 100%;
    height: 100%;
    font-family: Calibri !important;
    color: Black;
    font-size: 14px;
}

.firstrow
{
    position: absolute;
    margin: 0px;
    left: 0;
    top: 0;
    background: url(../Content/Images/header.jpg) repeat-x center top;
    color: White;
    font-weight: bold;
    text-align: center;

}
#fixedtable tr td
{
    padding: 5px !important;
    border: 1px solid #FFFFFF;
    text-align: center;
}

I am calculating the width of td21 with $('.td21').width() and assigning the width to td11 like $('td11').width($('.td21').width()) .

The problem is that the widths applying are not same, they vary by 1px and I could not find how this 1px difference occur. The .td21 width is 1px greater than .td11 .

Can any one please help me to find the solution?

Answer 1

<div id="div-1" style="width: 1000px;">
    <div id="div-2" style="width: 10%;"></div>
</div>

<script language="javascript">                
    var percents = parseInt(document.getElementById("div-2").style.width);
    var parentWidth = parseInt(document.getElementById("div-1").style.width);
    var pixels = parentWidth*(percents/100);
    alert(pixels); // will print "100"
</script>

Answer 2

尝试使用.outerWidth（）而不是.width()

Answer 3

This happens when you use percent + padding. Pixel is int and so it will be rounded.

In your example: 10%, 20% and 70% is the width of the container and than you need to add the padding and border.

With this decimal numbers will occur and than need to be rounded.

EXAMPLE:

Your page is 900px width. Without padding, margin or border you will have widths of 630px (70%), 160px (20%), 90px (10%).

But when you add the border + padding the percents must be calculated from 900 - (3 tds * 10px padding (left and right)) - (3 tds * 2px border(left and right)) = 864px.

With 864px width you will get: 604,8px (70%), 172,8px (20%), 86,4px (10%).

And this is where the 1px difference occures.