使用js实现密码框中密码的显示与隐藏，图标引用bootstrap里面的fontawesome样式
（复制整个 font-awesome 文件夹到您的项目中）
还需要引入文件
<link rel="stylesheet" type="text/css" href="bootstrap.min.css">
<link rel="stylesheet" type="text/css" href="Font-Awesome/css/font-awesome.min.css">
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>密码框</title>
<link rel="stylesheet" type="text/css" href="bootstrap.min.css">
<link rel="stylesheet" type="text/css" href="Font-Awesome/css/font-awesome.min.css">
</head>
<body>
<div class="content">
<div class="input_block">
<i class="fa fa-eye" onclick="hideShowPsw()" id="eye"></i>
<input type="password" id="password" placeholder="密码"/>
</div>
</div>
<script type="text/javascript">
var eye = document.getElementById("eye");
var password = document.getElementById("password");
//隐藏text block，显示password block
function hideShowPsw(){
if (password.type == "password") {
password.type = "text";
eye.className='fa fa-eye-slash'
}else {
password.type = "password";
eye.className='fa fa-eye'
}
}
</script>
</body>
</html>