之前做的通行证项目，里面的注册模块中输入密码需要显示密码强度（低中高）。当然这只是一个很简单的密码强度显示功能，不像网上那么复杂，能够满足一般的需求。
function PasswordStrength(passwordID,strengthID){ var _this = this; _this.init(strengthID); document.getElementById(passwordID).onkeyup = function(){ _this.checkStrength(this.value); }}PasswordStrength.prototype.init = function(strengthID){ var id = document.getElementById(strengthID); var div = document.createElement('div'); var strong = document.createElement('strong'); this.oStrength = id.appendChild(div); this.oStrengthTxt = id.parentNode.appendChild(strong);}PasswordStrength.prototype.checkStrength = function (val){ var aLvTxt = ['','低','中','高']; var lv = 0; if(val.match(/[a-z]/g)){lv++;} if(val.match(/[0-9]/g)){lv++;} if(val.match(/(.[^a-z0-9])/g)){lv++;} if(val.length < 6){lv=0;} if(lv > 3){lv=3;} this.oStrength.className = 'strengthLv' + lv; this.oStrengthTxt.innerHTML = aLvTxt[lv];}
<!DOCTYPE HTML><html lang="en"><head> <meta charset="utf-8"/> <title>密码强度</title> <style> #passStrength{height:6px;width:120px;border:1px solid #ccc;padding:2px;} .strengthLv1{background:red;height:6px;width:40px;} .strengthLv2{background:orange;height:6px;width:80px;} .strengthLv3{background:green;height:6px;width:120px;} </style></head><body> <input type="password" name="pass" id="pass" maxlength="16"/> <div class="pass-wrap"> <em>密码强度：</em> <div id="passStrength"></div> </div></body></html><script src="js/passwordStrength.js"></script><script>window.onload = function(){ new PasswordStrength('pass','passStrength');}</script>
