phpjs/_octopress/source/functions/strlen/index.markdown

php.js offers community built php functions in javascript

---
layout: page
title: "JavaScript strlen function"
comments: true
sharing: true
footer: true
alias:
- /functions/view/strlen:539
- /functions/view/strlen
- /functions/view/539
- /functions/strlen:539
- /functions/539
---
<!-- Generated by Rakefile:build -->
A JavaScript equivalent of PHP's strlen

{% codeblock strings/strlen.js lang:js https://raw.github.com/kvz/phpjs/master/functions/strings/strlen.js raw on github %}
function strlen (string) {
  // From: http://phpjs.org/functions
  // +   original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // +   improved by: Sakimori
  // +      input by: Kirk Strobeck
  // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // +   bugfixed by: Onno Marsman
  // +    revised by: Brett Zamir (http://brett-zamir.me)
  // %        note 1: May look like overkill, but in order to be truly faithful to handling all Unicode
  // %        note 1: characters and to this function in PHP which does not count the number of bytes
  // %        note 1: but counts the number of characters, something like this is really necessary.
  // *     example 1: strlen('Kevin van Zonneveld');
  // *     returns 1: 19
  // *     example 2: strlen('A\ud87e\udc04Z');
  // *     returns 2: 3
  var str = string + '';
  var i = 0,
    chr = '',
    lgth = 0;

  if (!this.php_js || !this.php_js.ini || !this.php_js.ini['unicode.semantics'] || this.php_js.ini['unicode.semantics'].local_value.toLowerCase() !== 'on') {
    return string.length;
  }

  var getWholeChar = function (str, i) {
    var code = str.charCodeAt(i);
    var next = '',
      prev = '';
    if (0xD800 <= code && code <= 0xDBFF) { // High surrogate (could change last hex to 0xDB7F to treat high private surrogates as single characters)
      if (str.length <= (i + 1)) {
        throw 'High surrogate without following low surrogate';
      }
      next = str.charCodeAt(i + 1);
      if (0xDC00 > next || next > 0xDFFF) {
        throw 'High surrogate without following low surrogate';
      }
      return str.charAt(i) + str.charAt(i + 1);
    } else if (0xDC00 <= code && code <= 0xDFFF) { // Low surrogate
      if (i === 0) {
        throw 'Low surrogate without preceding high surrogate';
      }
      prev = str.charCodeAt(i - 1);
      if (0xD800 > prev || prev > 0xDBFF) { //(could change last hex to 0xDB7F to treat high private surrogates as single characters)
        throw 'Low surrogate without preceding high surrogate';
      }
      return false; // We can pass over low surrogates now as the second component in a pair which we have already processed
    }
    return str.charAt(i);
  };

  for (i = 0, lgth = 0; i < str.length; i++) {
    if ((chr = getWholeChar(str, i)) === false) {
      continue;
    } // Adapt this line at the top of any loop, passing in the whole string and the current iteration and returning a variable to represent the individual character; purpose is to treat the first part of a surrogate pair as the whole character and then ignore the second part
    lgth++;
  }
  return lgth;
}
{% endcodeblock %}

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

### Example 1
This code
{% codeblock lang:js example %}
strlen('Kevin van Zonneveld');
{% endcodeblock %}

Should return
{% codeblock lang:js returns %}
19
{% endcodeblock %}

### Example 2
This code
{% codeblock lang:js example %}
strlen('A\ud87e\udc04Z');
{% endcodeblock %}

Should return
{% codeblock lang:js returns %}
3
{% endcodeblock %}


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