js input img图片预览

<script type="text/javascript">


function preImg(sourceId, targetId) {  
    if (typeof FileReader === 'undefined') {  
        alert('Your browser does not support FileReader...');  
        return;  
    }  
    var reader = new FileReader();  
  
    reader.onload = function(e) {  
        var img = document.getElementById(targetId);  
        img.src = this.result;  
    }  
    reader.readAsDataURL(document.getElementById(sourceId).files[0]);  
}  

</script>

<input type="file" class="form-control"  name="imgOne" id="imgOne" onchange="preImg(this.id,'imgPre');"  style="width: 300px">

<img id="imgPre" src="" style="display: block;"  class="img-responsive"   />