This article shares the specific code for implementing the JavaScript image preview function for your reference. The specific content is as follows
First, I will share with you a code about js image preview, which is compatible with Firefox and Google Chrome
/* Case display image preview*/$(function(){ $("#file0").bind("change",function(){ clickupLoad(); });});function clickupLoad(){ var imgObject = document.getElementById('file0'); var getImageSrc = getFullPath(imgObject); // Local path var srcs = window.URL.createObjectURL(imgObject.files[0]); var pos = getImageSrc.lastIndexOf("."); var lastname = getImageSrc.substring(pos, getImageSrc.length) // Image suffix] if(srcs!=""){ $("#yulan2").attr("src",srcs); }else{ alert("Please select an image"); } }function getFullPath(obj) { //Get the full path of the image if (obj) { if (window.navigator.userAgent.indexOf("MSIE") >= 1){ obj.select(); return document.selection.createRange().text; }else if(window.navigator.userAgent.indexOf("Firefox") >= 1) { if (obj.files) { return window.URL.createObjectURL(obj.files[0]); } return obj.value; } return obj.value; }}The example code implements the timely preview of the image upload by js:
<html><head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Image Upload Local Preview</title> <style type="text/css">#preview{width:260px;height:190px;border:1px solid #000;overflow:hidden;}#imghead {filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);}</style><script type="text/javascript"> //IE uses filters for uploading and previewing pictures. function previewImage(file) { var MAXWIDTH = 260; var MAXHEIGHT = 180; var div = document.getElementById('preview'); if (file.files && file.files[0]) { div.innerHTML ='<img id=imghead>'; var img = document.getElementById('imghead'); img.onload = function(){ var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight); img.width = rect.width; img.height = rect.height;// img.style.marginLeft = rect.left+'px'; img.style.marginTop = rect.top+'px'; } var reader = new FileReader(); reader.onload = function(evt){img.src = evt.target.result;} reader.readAsDataURL(file.files[0]); } else // Compatible with IE { var sFilter='filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="'; file.select(); var src = document.selection.createRange().text; div.innerHTML = '<img id=imghead>'; var img = document.getElementById('imghead'); img.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = src; var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight); status =('rect:'+rect.top+','+rect.left+','+rect.width+','+rect.height); div.innerHTML = "<div id=divhead style='width:"+rect.width+"px;height:"+rect.height+"px;margin-top:"+rect.top+"px;"+sFilter+src+"/"'></div>"; } } function clacImgZoomParam(maxWidth, maxHeight, width, height ){ var param = {top:0, left:0, width:width, height:height}; if( width>maxWidth || height>maxHeight ) { rateWidth = width / maxWidth; rateHeight = height / maxHeight; if( rateWidth > rateHeight ) { param.width = maxWidth; param.height = Math.round(height / rateWidth); }else { param.width = Math.round(width / rateHeight); param.height = maxHeight; } } param.left = Math.round((maxWidth - param.width) / 2); param.top = Math.round((maxHeight - param.height) / 2); return param; }</script> </head> <body><div id="preview"> <img id="imghead" width=100 height=100 border=0 src='<%=request.getContextPath()%>/images/default.jpg'></div><input type="file" onchange="previewImage(this)" /> </body> </html>The above is all about this article, I hope it will be helpful for everyone to learn JavaScript programming.