toLowerCase() & toUpperCase() on a string return that same string, with the cases converted to either lower or upper cases:
var inconsistent = “Up AnD dOwn”; console.log(inconsistent.toLowerCase()); // “up and down”
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// toLowerCase() myString.toLowerCase(); // toUpperCase myString.toUpperCase();
Notes on Usage
This is most useful when comparing strings because you can ignore case inconsistencies and focus on the actual words. While there are times you need to check for cases, this has you covered for the times that you don’t:
var typeface = "Sans-serif"; console.log(typeface.toLowerCase() == "sans-serif"); // true