模拟placeholder支持ie8以下处理了密码框只读的问题

时间：2024-07-23 18:06:44
<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>Document</title>

</head>

<body>

    <form id="form1" action="">

        <input type="text" name="username" placeholder="请输入用户名">

        <input type="password" name="password" placeholder="请输入密码">

        <input type="password" name="password2" placeholder="请确认密码">

        <input type="text" name="email" placeholder="请输入邮箱">

    </form>

    <script type="text/javascript">

        (function(){

            //检测是否支持placeholder

            if('placeholder' in document.createElement('input')) return;

            var form = document.getElementById('form1'),

                inputs = form.getElementsByTagName('input'),

                i,input,value,type;

            //获取焦点事件

            var focus = function(value,type){

                return function(){

                    if(this.value === value) this.value = '';

                    if(this.value === '' && type === 'password'){

                        try {

                            this.type = 'password';

                        }catch(e){

                            this.style.visibility = 'hidden';

                            this.style.position = 'absolute';

                            this.nextSibling.style.visibility = 'visible';

                            this.nextSibling.style.position = 'relative';

                            //定位光标

                            this.nextSibling.focus();

                        }

                    }

                };

            };

            //失去焦点事件

            var blur = function(value,type){

                return function(){

                    if(this.value === '') this.value = value;

                    if(this.value === value && type === 'password'){

                        try{

                            this.type = 'text';

                        }catch(e){

                            this.style.visibility = 'hidden';

                            this.style.position = 'absolute';

                            this.previousSibling.style.visibility = 'visible';

                            this.previousSibling.style.position = 'relative';

                        }

                    }

                };

            };

            //如果浏览器是ie8以下，则创建一个文本框与密码框切换显示

            var createInput = function(value,type,type2){

                var tmp = document.createElement('input');

                tmp.type = type;

                tmp.name = this.name;

                tmp.placeholder = value;

                tmp.value = value;

                tmp.onfocus = focus(value,type2);

                tmp.onblur = blur(value,type2);

                form.insertBefore(tmp,this);

                this.style.visibility = 'hidden';

                this.style.position = 'absolute';

            }

            for(i=0;i<inputs.length;i++){

                input = inputs[i];

                //不是文本框跳过

                if(input.type !== 'text' && input.type !== 'password') continue;

                type = 'text';

                value = input.getAttribute('placeholder');

                if(input.type === 'password'){

                    type = 'password'; //给密码框做一个标记

                    //ie8以下input type是只读的

                    try {

                        input.type = 'text';

                    }catch(e){

                        createInput.call(input,value,'text',type);

                        i++;

                    }

                }

                input.value = value;

                input.onfocus = focus(value,type);

                input.onblur = blur(value,type);

            }

        })();

    </script>

</body>

</html>

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