JavaScriptでパスワード生成

やりたいこと

記号大文字小文字数字を含むパスワード生成

mkpass.html

<form name="makepass">
	<input type="button" value="exec" onclick="makePass()">
	<input type="text" size="1" id="passcount" style="text-align:center" value="10">
	<input type="checkbox" id="kigou" checked>記号あり
	<input type="text" size="15"  name="pass" readonly="readonly">
</form>

<script type="text/javascript">

window.onload = function () {
	makePass();
}

function makePass() {
	var passLen = document.makepass.passcount.value;
	var pass = "";
	var lower = "abcdefghijklmnopqrstuvwxyz";
	var upper = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	var num = "0123456789";
	var kigou = "!#$%&=/*-+^{}()";
	var kigoucount,lowercount,uppercount;
	var aryIndex = [];
	var aryKigouNum = [];
	var aryLowerNum = [];
	var aryUpperNum = [];
	
	let checkKigou = document.makepass.kigou.checked;
	if (checkKigou == true) {
		kigoucount = Math.floor(Math.random() * ( passLen - 3 ) + 1);
	}else {
		kigoucount = 0;
	}
	aryIndex = [...Array(Number(passLen))].map((_, i) => i);
	lowercount = Math.floor(Math.random() * ( passLen - kigoucount -2 ) + 1);
	uppercount = Math.floor(Math.random() * ( passLen - kigoucount - lowercount -1 ) + 1);
	for(var i=0; i < kigoucount; i++){
		aryKigouNum.push(aryIndex.splice(Math.floor(Math.random() * aryIndex.length), 1));
	}
	for(var i=0; i < lowercount; i++){
		aryLowerNum.push(aryIndex.splice(Math.floor(Math.random() * aryIndex.length), 1));
	}
	for(var i=0; i < uppercount; i++){
		aryUpperNum.push(aryIndex.splice(Math.floor(Math.random() * aryIndex.length), 1));
	}
	for(var i=0;i<passLen;i++){
		if (aryKigouNum.find(element => element == i)) { 
			pass += kigou.charAt(Math.floor(Math.random() * kigou.length));
		}else if (aryLowerNum.find(element => element == i)) {
			pass += lower.charAt(Math.floor(Math.random() * lower.length));
		}else if (aryUpperNum.find(element => element == i)) {
			pass += upper.charAt(Math.floor(Math.random() * upper.length));
		}else {
			pass += num.charAt(Math.floor(Math.random() * num.length));
		}
	}
	console.log("aryKigouNum:" + aryKigouNum);	//aryKigouNum:3,9
	console.log("aryLowerNum:" + aryLowerNum);	//aryLowerNum:2,1
	console.log("aryUpperNum:" + aryUpperNum);	//aryUpperNum:8,6,0
	console.log("aryIndex:" + aryIndex);		//aryIndex:4,5,7
												//     0123456789
	console.log("pass:" + pass);				//pass:Usf)00N8S*
	document.makepass.pass.value = pass;
}

</script>

参考にさせていただいた