css-content-escape.js

var safeCharsForCSSContent = /[0-9A-Za-z\`\~\!\@\#\$\%\^\&\*\(\)\-\_\=\+\|\[\{\]\}\:\,<\.\>\/\?]/;
  var singleEscapeChars = /[\\\;]/;
  function escapeForCSSContent(text) {
    var index = 0,
        length = text ? text.length : 0,
        result = '';

    while(index < length) {
      var character = text.charAt(index);
      if (safeCharsForCSSContent.test(character)) {
        result += character;
      } else if (singleEscapeChars.test(character)) {
        result += '\\' + character;
      } else {
        var charCode = character.charCodeAt(0),
            hexCode = charCode.toString(16).toUpperCase(),
            escaped = '\\' + ('0000' + hexCode).slice(-4) + ' ';
        result += escaped;
      }
      index++;
    }
    return result;
  }