实操中感觉比较省事的代码

js随机生产6位数字

function code() {
        var num = "";
        for (var i = 0;i < 6;i++) {
            num += Math.floor(Math.random()*10);
        }
        document.getElementById("codes").value = num;
    }

bootstrap实现input内置图标

<div class="input-group">
    <input type="text" class="form-control" id="search" placeholder="搜索手机号/姓名" name="keyword" style="">
    <span class="glyphicon glyphicon-remove-circle" id="remove" style="position:absolute;top:10px;right:70px;z-index:10"></span>
    <span class="input-group-btn">
        <button class="btn btn-default" type="button">搜索</button>
    /span>
</div>

js实现图片预览

<form action="" enctype="multipart/form-data">
    <input id="file" class="filepath" onchange="changepic(this)" type="file"><br>
    <img src="" id="show" width="200">
</form>
<script>
    function changepic() {
        var reads= new FileReader();
        f=document.getElementById('file').files[0];
        reads.readAsDataURL(f);
        reads.onload=function (e) {
            document.getElementById('show').src=this.result;
        };
    }
</script>