---
layout: page
title: "JavaScript substr_replace function"
comments: true
sharing: true
footer: true
alias:
- /functions/view/substr_replace:819
- /functions/view/substr_replace
- /functions/view/819
- /functions/substr_replace:819
- /functions/819
---
<!-- Generated by Rakefile:build -->
A JavaScript equivalent of PHP's substr_replace

{% codeblock strings/substr_replace.js lang:js https://raw.github.com/kvz/phpjs/master/functions/strings/substr_replace.js raw on github %}
function substr_replace (str, replace, start, length) {
  // From: http://phpjs.org/functions
  // +   original by: Brett Zamir (http://brett-zamir.me)
  // *     example 1: substr_replace('ABCDEFGH:/MNRPQR/', 'bob', 0);
  // *     returns 1: 'bob'
  // *     example 2: $var = 'ABCDEFGH:/MNRPQR/';
  // *     example 2: substr_replace($var, 'bob', 0, $var.length);
  // *     returns 2: 'bob'
  // *     example 3: substr_replace('ABCDEFGH:/MNRPQR/', 'bob', 0, 0);
  // *     returns 3: 'bobABCDEFGH:/MNRPQR/'
  // *     example 4: substr_replace('ABCDEFGH:/MNRPQR/', 'bob', 10, -1);
  // *     returns 4: 'ABCDEFGH:/bob/'
  // *     example 5: substr_replace('ABCDEFGH:/MNRPQR/', 'bob', -7, -1);
  // *     returns 5: 'ABCDEFGH:/bob/'
  // *     example 6: substr_replace('ABCDEFGH:/MNRPQR/', '', 10, -1)
  // *     returns 6: 'ABCDEFGH://'

  if (start < 0) { // start position in str
    start = start + str.length;
  }
  length = length !== undefined ? length : str.length;
  if (length < 0) {
    length = length + str.length - start;
  }

  return str.slice(0, start) + replace.substr(0, length) + replace.slice(length) + str.slice(start + length);
}
{% endcodeblock %}

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

### Example 1
This code
{% codeblock lang:js example %}
substr_replace('ABCDEFGH:/MNRPQR/', 'bob', 0);
{% endcodeblock %}

Should return
{% codeblock lang:js returns %}
'bob'
{% endcodeblock %}

### Example 2
This code
{% codeblock lang:js example %}
$var = 'ABCDEFGH:/MNRPQR/';
substr_replace($var, 'bob', 0, $var.length);
{% endcodeblock %}

Should return
{% codeblock lang:js returns %}
'bob'
{% endcodeblock %}

### Example 3
This code
{% codeblock lang:js example %}
substr_replace('ABCDEFGH:/MNRPQR/', 'bob', 0, 0);
{% endcodeblock %}

Should return
{% codeblock lang:js returns %}
'bobABCDEFGH:/MNRPQR/'
{% endcodeblock %}


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