javascript 密码强度验证规则、打分、验证（给出前端代码，后端代码可根据强度规则翻译）

function passwordGrade(pwd) {
var score = 0;
var regexArr = [[0-9], [a-z], [A-Z], [\\W_]];
var repeatCount = 0;
var prevChar = ;
//check length
var len = pwd.length;
score += len > 18 ? 18 : len;
//check type
for (var i = 0, num = regexArr.length; i < num; i++) { if (eval(/ + regexArr[i] + /).test(pwd)) score += 4; }
//bonus point
for (var i = 0, num = regexArr.length; i < num; i++) {
if (pwd.match(eval(/ + regexArr[i] + /g)) && pwd.match(eval(/ + regexArr[i] + /g)).length >= 2) score += 2;
if (pwd.match(eval(/ + regexArr[i] + /g)) && pwd.match(eval(/ + regexArr[i] + /g)).length >= 5) score += 2;
}
//deduction
for (var i = 0, num = pwd.length; i < num; i++) {
if (pwd.charAt(i) == prevChar) repeatCount++;
else prevChar = pwd.charAt(i);
}
score -= repeatCount * 1;
return score;
}