如果使用JavaScript以其他字符串开头将其剥离

Question

Using JavaScript, how do I strip a string from other string if the other string starts with the first string?

var matcher='Hello';

var s1='hello everyone';
console.log(someFunction(s1,matcher);
//Should return ' everyone', and should be case insensitive

var s2='xhello everyone';
console.log(someFunction(s2,matcher);
//Should return nothing (either NULL or FALSE or "" would be fine) since s2 doesn't start with 'Hello'

Demo for the three answers: https://jsfiddle.net/dynvgn1k/

Answer 1

No need to use regex just use:

s1.toLowerCase().indexOf(matcher.toLowerCase()) === 0 && s1.substr(matcher.length)
//=>  everyone

matcher='hi'
s1.toLowerCase().indexOf(matcher.toLowerCase()) === 0 && s1.substr(matcher.length)
//=> false

Use of toLowerCase will make it ignore case comparison. indexOf returns position of search string in subject and position 0 means search word is found at start.

Answer 2

A simple regex will do it

function someFunction(str,matcher) {
    var regex = new RegExp('^' + matcher, 'i');
    return str.replace(regex, '');
}

Answer 3

You can do like this

var matcher='Hello';
var s1='hello everyone';
s=s1.split(" ");
(s[0].toUpperCase() ===matcher.toUpperCase() )?console.log(s[1]):console.log("nothing");