String.prototype.prune() is the opposite of String.prototype.slice(). It removes the specified portion of the string and returns what's left, without modifying the original string.

stringPrune.js

//returns a copy of a string with a portion removed
//(essentially the opposite of `slice`)
//the `end` argument is optional

//str.prune(begin[, end])

if(!String.prototype.prune){
	String.prototype.prune = function prune(begin, end){
		"use strict";
		var newStr = this.slice(0);	//make a copy of the string
		
		//make `begin` a positive index
		if(!begin) begin = 0;
		else if(begin < 0) begin = Math.max(0, this.length+begin);
		
		//try to make `end` a positive index
		if(isUndefined(end)) end = this.length;
		else if(!end) end = 0;
		else if(end < 0) end = this.length+end;
		
		if(end < begin){
			return newStr.slice(end, begin);	//remove specified elements
		}
		else{
			return newStr.slice(0, begin) + newStr.slice(end);	//remove specified elements
		}
	};
}