Random strings generator

randomString.js

function randomString(length,numNumeric,numLCase,numUCase,numSymbols){
	length=length||16;numNumeric=numNumeric||3,numLCase=numLCase||3,numUCase=numUCase||3,numSymbols=numSymbols||3;
	var charsList = [
		'0123456789',
		'abcdefghijklmnopqrstuvwxyz',
		'ABCDEFGHIJKLMNOPQRSTUVWXYZ',
		'!"#$%&\'()*+,-./\\:;<=>?@[]^_`{|}~'
	],
	charLength = [numNumeric,numLCase,numUCase,numSymbols],
	str="",i=0;
	while(i<length){
		skipchars=true,j=0;
		while(skipchars&&j<4){
			charsType=Math.floor(Math.random()*charsList.length);
			numCharsCount = charLength[charsType];
			if(numCharsCount > 0) skipchars=false;
			j++;
		}
		if(j>=4)
			charsType=Math.floor(Math.random()*(charsList.length-1));
    	str+=charsList[charsType][Math.floor(Math.random()*charsList[charsType].length)];
			charLength[charsType]--;i++;
	}
	return str;
}

Reinvent the wheel.