html：

<div class="uploadpit">
  <div class="uploadpit-btn"><span>上傳圖片</span>
     <input type="file" value="上傳圖片" onchange="imgPreview(this,'preview_img')" accept="image/*" id="file5" multiple='multiple'>
  </div>
                         
  <div class="preview priv_textword_img" id="preview_img">                             
  </div>
</div>

關於樣式，給input ，opacity:0;  (ie兼容性問題，之前文章寫有)。

js:

function imgPreview(obj,id) {

    var fl = obj.files.length;
    for (var i = 0; i < fl; i++) {
        var file = obj.files[i];

        console.log(file)

        var reader = new FileReader();
        //讀取文件過程方法    
        reader.onloadstart = function(e) {
            console.log("開始讀取....");
        }
        reader.onprogress = function(e) {
            console.log("正在讀取中....");
        }
        reader.onabort = function(e) {
            console.log("中斷讀取....");
        }
        reader.onerror = function(e) {
            console.log("讀取異常....");
        }
        reader.onload = function(e) {
            console.log("成功讀取....");
            if ((file.size / 1024).toFixed(0) > 4096) {
                alert("上傳圖片不得超過4M！")
                return false;
            } else {
                var imgstr = '<img style="width:100%;" src="' + e.target.result + '"/>';
                var oimgbox = document.getElementById(id);
                var ndiv = document.createElement("li");

                ndiv.innerHTML = imgstr;
                ndiv.className = "img-div";
                oimgbox.appendChild(ndiv);
            }

        }

        reader.readAsDataURL(file);
    }

}