---
layout: page
title: "JavaScript addcslashes function"
comments: true
sharing: true
footer: true
alias:
- /functions/view/addcslashes:879
- /functions/view/addcslashes
- /functions/view/879
- /functions/addcslashes:879
- /functions/879
---
<!-- Generated by Rakefile:build -->
A JavaScript equivalent of PHP's addcslashes

{% codeblock strings/addcslashes.js lang:js https://raw.github.com/kvz/phpjs/master/functions/strings/addcslashes.js raw on github %}
function addcslashes (str, charlist) {
  // From: http://phpjs.org/functions
  // +   original by: Brett Zamir (http://brett-zamir.me)
  // %  note 1: We show double backslashes in the return value example code below because a JavaScript string will not
  // %  note 1: render them as backslashes otherwise
  // *     example 1: addcslashes('foo[ ]', 'A..z'); // Escape all ASCII within capital A to lower z range, including square brackets
  // *     returns 1: "\\f\\o\\o\\[ \\]"
  // *     example 2: addcslashes("zoo['.']", 'z..A'); // Only escape z, period, and A here since not a lower-to-higher range
  // *     returns 2: "\\zoo['\\.']"
  // *     example 3: addcslashes("@a\u0000\u0010\u00A9", "\0..\37!@\177..\377"); // Escape as octals those specified and less than 32 (0x20) or greater than 126 (0x7E), but not otherwise
  // *     returns 3: '\\@a\\000\\020\\302\\251'
  // *     example 4: addcslashes("\u0020\u007E", "\40..\175"); // Those between 32 (0x20 or 040) and 126 (0x7E or 0176) decimal value will be backslashed if specified (not octalized)
  // *     returns 4: '\\ ~'
  // *     example 5: addcslashes("\r\u0007\n", '\0..\37'); // Recognize C escape sequences if specified
  // *     returns 5: "\\r\\a\\n"
  // *     example 6: addcslashes("\r\u0007\n", '\0'); // Do not recognize C escape sequences if not specified
  // *     returns 6: "\r\u0007\n"
  var target = '',
    chrs = [],
    i = 0,
    j = 0,
    c = '',
    next = '',
    rangeBegin = '',
    rangeEnd = '',
    chr = '',
    begin = 0,
    end = 0,
    octalLength = 0,
    postOctalPos = 0,
    cca = 0,
    escHexGrp = [],
    encoded = '',
    percentHex = /%([\dA-Fa-f]+)/g;
  var _pad = function (n, c) {
    if ((n = n + '').length < c) {
      return new Array(++c - n.length).join('0') + n;
    }
    return n;
  };

  for (i = 0; i < charlist.length; i++) {
    c = charlist.charAt(i);
    next = charlist.charAt(i + 1);
    if (c === '\\' && next && (/\d/).test(next)) { // Octal
      rangeBegin = charlist.slice(i + 1).match(/^\d+/)[0];
      octalLength = rangeBegin.length;
      postOctalPos = i + octalLength + 1;
      if (charlist.charAt(postOctalPos) + charlist.charAt(postOctalPos + 1) === '..') { // Octal begins range
        begin = rangeBegin.charCodeAt(0);
        if ((/\\\d/).test(charlist.charAt(postOctalPos + 2) + charlist.charAt(postOctalPos + 3))) { // Range ends with octal
          rangeEnd = charlist.slice(postOctalPos + 3).match(/^\d+/)[0];
          i += 1; // Skip range end backslash
        } else if (charlist.charAt(postOctalPos + 2)) { // Range ends with character
          rangeEnd = charlist.charAt(postOctalPos + 2);
        } else {
          throw 'Range with no end point';
        }
        end = rangeEnd.charCodeAt(0);
        if (end > begin) { // Treat as a range
          for (j = begin; j <= end; j++) {
            chrs.push(String.fromCharCode(j));
          }
        } else { // Supposed to treat period, begin and end as individual characters only, not a range
          chrs.push('.', rangeBegin, rangeEnd);
        }
        i += rangeEnd.length + 2; // Skip dots and range end (already skipped range end backslash if present)
      } else { // Octal is by itself
        chr = String.fromCharCode(parseInt(rangeBegin, 8));
        chrs.push(chr);
      }
      i += octalLength; // Skip range begin
    } else if (next + charlist.charAt(i + 2) === '..') { // Character begins range
      rangeBegin = c;
      begin = rangeBegin.charCodeAt(0);
      if ((/\\\d/).test(charlist.charAt(i + 3) + charlist.charAt(i + 4))) { // Range ends with octal
        rangeEnd = charlist.slice(i + 4).match(/^\d+/)[0];
        i += 1; // Skip range end backslash
      } else if (charlist.charAt(i + 3)) { // Range ends with character
        rangeEnd = charlist.charAt(i + 3);
      } else {
        throw 'Range with no end point';
      }
      end = rangeEnd.charCodeAt(0);
      if (end > begin) { // Treat as a range
        for (j = begin; j <= end; j++) {
          chrs.push(String.fromCharCode(j));
        }
      } else { // Supposed to treat period, begin and end as individual characters only, not a range
        chrs.push('.', rangeBegin, rangeEnd);
      }
      i += rangeEnd.length + 2; // Skip dots and range end (already skipped range end backslash if present)
    } else { // Character is by itself
      chrs.push(c);
    }
  }

  for (i = 0; i < str.length; i++) {
    c = str.charAt(i);
    if (chrs.indexOf(c) !== -1) {
      target += '\\';
      cca = c.charCodeAt(0);
      if (cca < 32 || cca > 126) { // Needs special escaping
        switch (c) {
        case '\n':
          target += 'n';
          break;
        case '\t':
          target += 't';
          break;
        case '\u000D':
          target += 'r';
          break;
        case '\u0007':
          target += 'a';
          break;
        case '\v':
          target += 'v';
          break;
        case '\b':
          target += 'b';
          break;
        case '\f':
          target += 'f';
          break;
        default:
          //target += _pad(cca.toString(8), 3);break; // Sufficient for UTF-16
          encoded = encodeURIComponent(c);

          // 3-length-padded UTF-8 octets
          if ((escHexGrp = percentHex.exec(encoded)) !== null) {
            target += _pad(parseInt(escHexGrp[1], 16).toString(8), 3); // already added a slash above
          }
          while ((escHexGrp = percentHex.exec(encoded)) !== null) {
            target += '\\' + _pad(parseInt(escHexGrp[1], 16).toString(8), 3);
          }
          break;
        }
      } else { // Perform regular backslashed escaping
        target += c;
      }
    } else { // Just add the character unescaped
      target += c;
    }
  }
  return target;
}
{% endcodeblock %}

 - [Raw function on GitHub](https://github.com/kvz/phpjs/blob/master/functions/strings/addcslashes.js)

Please note that php.js uses JavaScript objects as substitutes for PHP arrays, they are 
the closest match to this hashtable-like data structure. 

Please also note that php.js offers community built functions and goes by the 
[McDonald's Theory](https://medium.com/what-i-learned-building/9216e1c9da7d). We'll put online 
functions that are far from perfect, in the hopes to spark better contributions. 
Do you have one? Then please just: 

 - [Edit on GitHub](https://github.com/kvz/phpjs/edit/master/functions/strings/addcslashes.js)

### Example 1
This code
{% codeblock lang:js example %}
addcslashes('foo[ ]', 'A..z'); // Escape all ASCII within capital A to lower z range, including square brackets
{% endcodeblock %}

Should return
{% codeblock lang:js returns %}
"\\f\\o\\o\\[ \\]"
{% endcodeblock %}

### Example 2
This code
{% codeblock lang:js example %}
addcslashes("zoo['.']", 'z..A'); // Only escape z, period, and A here since not a lower-to-higher range
{% endcodeblock %}

Should return
{% codeblock lang:js returns %}
"\\zoo['\\.']"
{% endcodeblock %}

### Example 3
This code
{% codeblock lang:js example %}
addcslashes("@a\u0000\u0010\u00A9", "\0..\37!@\177..\377"); // Escape as octals those specified and less than 32 (0x20) or greater than 126 (0x7E), but not otherwise
{% endcodeblock %}

Should return
{% codeblock lang:js returns %}
'\\@a\\000\\020\\302\\251'
{% endcodeblock %}


### Other PHP functions in the strings extension
{% render_partial _includes/custom/strings.html %}