Correctly Adding Unit to Number

When converting a unitless number to a length, duration, angle or whatever, people tend to simply append the unit as a string, like this:

$value: 42;
$length: $value + px;
// 42px

While this method works, it is far from ideal because it results in implicitly casting the initial value as a string. Indeed, if you try doing math with the $length value from now on, you'll see that Sass quickly throws an error because it cannot do math operators with a string.

To work around this issue, there are two ways of doing this properly:

$value: 42;
$length: $value + 0px;
// 42px
$value: 42;
$length: $value * 1px;
// 42px

Any of those methods will correctly produce a number as expected and not a string.


  1. User Avatar
    Permalink to comment#

    I use the last method, and it works fine.

  2. User Avatar
    Linus Miller

    Multiplication is a far more complicated operation for a computer to do that addition. So always use the first one.

  3. User Avatar
    Permalink to comment#

    $value3:$value1+$value2; // 1px2px

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