The startsWith()
method determines whether a string begins with the characters of another string, returning true
or false
as appropriate.
str.startsWith(searchString[, position])
searchString
position
searchString
; defaults to 0.This method lets you determine whether or not a string begins with another string.
startsWith()
var str = 'To be, or not to be, that is the question.'; console.log(str.startsWith('To be')); // true console.log(str.startsWith('not to be')); // false console.log(str.startsWith('not to be', 10)); // true
This method has been added to the ECMAScript 6 specification and may not be available in all JavaScript implementations yet. However, you can polyfill str.startsWith()
with the following snippet:
if (!str.startsWith) { str.startsWith = function(searchString, position) { position = position || 0; return this.indexOf(searchString, position) === position; }; }
A more robust and optimized Polyfill is available str.startsWith">on GitHub by Mathias Bynens.
Created by Mozilla Contributors, license: CC-BY-SA 2.5