Javascript Case Insensitive String Compare

0-JS-INSENSITIVE-COMPARE.MD

JAVASCRIPT CASE INSENSITIVE STRING COMPARE

https://code-boxx.com/case-insensitive-string-comparison-javascript/

LICENSE

Copyright by Code Boxx

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

1-lower-upper-case.js

// (A) STRINGS
var first = "Hello World";
var second = "hello world";

// (B) COMPARISON
console.log(first == second); // false
console.log(first.toLowerCase() == second.toLowerCase()); // true
console.log(first.toUpperCase() == second.toUpperCase()); // true

2a-locale-compare.js

// (A) VARIABLES
var first, second;

// (B) LOCALE COMPARE
// (B1) RETURNS 0 WHEN BOTH FIRST & SECOND ARE EQUAL
first = "C"; second = "C";
console.log(first.localeCompare(second)); // 0 (equal)

// (B2) RETURNS 1 WHEN FIRST IS AFTER SECOND
first = "C"; second = "B";
console.log(first.localeCompare(second)); // 1 (c is after b)

// (B3) RETURNS -1 WHEN FIRST IS BEFORE SECOND
first = "A"; second = "B";
console.log(first.localeCompare(second)); // -1 (a is before b)

// (C) CAN ALSO COMPARE "COMPLEX STRINGS"
first = "Car"; second = "Cow";
console.log(first.localeCompare(second)); // -1 (car is before cow)
console.log(second.localeCompare(first)); // 1 (cow is after car)

2b-locale-compare.js

// (A) STRINGS
var first = "CAR";
var second = "car";

// (B) DEFAULT LOCALE COMPARE
// This will most likely return 1.
// Capital "CAR" has precedence over small "car".
console.log(first.localeCompare(second));

// (C) LOCALE COMPARE WITH OPTIONS
// Set to case-insensitive compare.
// This will now return 0.
console.log(
  first.localeCompare(second, "en", {
    sensitivity: "base",
    ignorePunctuation: true
  })
);

3-regex.js

// (A) THE SETING
var thestring = "COW";

// (B) CASE SENSITIVE PATTERN MATCHING
var pattern = /^cow$/;                // must match "cow" exactly
console.log(pattern.test(thestring)); // false

// (C) CASE INSENSITIVE PATTERN MATCHING
var pattern = /^cow$/i;               // match "cow"
console.log(pattern.test(thestring)); // true