Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.9)
// Compass (v1.0.1)
// ----

/// Trim `$string`
/// @param {String} $string - String to trim
/// @return {String}
@function trim($string) {
  @return str-slice(
    $string, 
    first-index($string, 'left'), 
    first-index($string, 'right')
  );
}

/// Find first char which is not a space
/// @param {String} $string - String
/// @param {String} $direction ['left'] - Either `left` or `right`
/// @return {Number}
@function first-index($string, $direction: 'left') {
  @for $i from 1 through str-length($string) {
    $index: if('left' == $direction, $i, -$i);
    
    @if ' ' != str-slice($string, $index, $index) {
      @return $index;
    }
  }
  
  @return 0;
}

.foo {
  content: trim('        ');
  content: trim('no spaces');
  content: trim('   3 spaces in front');
  content: trim('   3 spaces in front and back   ');
  content: trim('          lots and lots of spaces');
}

SassMeister-output.css

.foo {
  content: "";
  content: "no spaces";
  content: "3 spaces in front";
  content: "3 spaces in front and back";
  content: "lots and lots of spaces";
}