PHP's strncasecmp in JavaScript

How to use

You you can install via yarn add locutus and require this function via const strncasecmp = require('locutus/php/strings/strncasecmp').

It is important to use a bundler that supports tree-shaking so that you only ship the functions that you actually use to your browser, instead of all of Locutus, which is massive. Examples are: Parcel, webpack, or rollup.js. For server-side use this is typically less of a concern.

Examples

Please note that these examples are distilled from test cases that automatically verify our functions still work correctly. This could explain some quirky ones.

#	code	expected result
1	strncasecmp('Price 12.9', 'Price 12.15', 2)	0
2	strncasecmp('Price 12.09', 'Price 12.15', 10)	-1
3	strncasecmp('Price 12.90', 'Price 12.15', 30)	8
4	strncasecmp('Version 12.9', 'Version 12.15', 20)	8
5	strncasecmp('Version 12.15', 'Version 12.9', 20)	-8

Notes

• Returns < 0 if str1 is less than str2 ; > 0 if str1 is greater than str2, and 0 if they are equal.

Here’s what our current JavaScript equivalent to PHP's strncasecmp looks like.

module.exports = function strncasecmp(argStr1, argStr2, len) {
  //  discuss at: https://locutus.io/php/strncasecmp/
  // original by: Saulo Vallory
  //    input by: Nate
  // bugfixed by: Onno Marsman (https://twitter.com/onnomarsman)
  //      note 1: Returns < 0 if str1 is less than str2 ; > 0
  //      note 1: if str1 is greater than str2, and 0 if they are equal.
  //   example 1: strncasecmp('Price 12.9', 'Price 12.15', 2)
  //   returns 1: 0
  //   example 2: strncasecmp('Price 12.09', 'Price 12.15', 10)
  //   returns 2: -1
  //   example 3: strncasecmp('Price 12.90', 'Price 12.15', 30)
  //   returns 3: 8
  //   example 4: strncasecmp('Version 12.9', 'Version 12.15', 20)
  //   returns 4: 8
  //   example 5: strncasecmp('Version 12.15', 'Version 12.9', 20)
  //   returns 5: -8

  let diff
  let i = 0
  const str1 = (argStr1 + '').toLowerCase().substr(0, len)
  const str2 = (argStr2 + '').toLowerCase().substr(0, len)

  if (str1.length !== str2.length) {
    if (str1.length < str2.length) {
      len = str1.length
      if (str2.substr(0, str1.length) === str1) {
        // return the difference of chars
        return str1.length - str2.length
      }
    } else {
      len = str2.length
      // str1 is longer than str2
      if (str1.substr(0, str2.length) === str2) {
        // return the difference of chars
        return str1.length - str2.length
      }
    }
  } else {
    // Avoids trying to get a char that does not exist
    len = str1.length
  }

  for (diff = 0, i = 0; i < len; i++) {
    diff = str1.charCodeAt(i) - str2.charCodeAt(i)
    if (diff !== 0) {
      return diff
    }
  }

  return 0
}

A community effort

Not unlike Wikipedia, Locutus is an ongoing community effort. Our philosophy follows The McDonald’s Theory. This means that we assimilate first iterations with imperfections, hoping for others to take issue with-and improve them. This unorthodox approach has worked very well to foster fun and fruitful collaboration, but please be reminded to use our creations at your own risk. THE SOFTWARE IS PROVIDED "AS IS" has never been more true than for Locutus.

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