前言：我們在做網頁時常常需要有上傳圖片的需求，可能是選擇圖片或拍照上傳，如果簡單的使用<input type=file/>這種方式雖然也能實現功能，但使用者體驗上可能會差了一些，所以本文記錄了使用css+js實現圖片選中後的預覽及壓縮上傳功能，部分帶來來自網絡，此處做了記錄整理。
效果預覽：
1.創建index.html<!DOCTYPE html><html> <head> <meta charset=UTF-8> <meta name=viewport content=width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no> <title>拍照上傳</title> <link rel=stylesheet href=index.css/> <script type='text/javascript' src='index.js' charset='utf-8'></script> </head> <body> <form id=mainForm> <div class=content> <div class=label>身分證</div> <div class=img-area> <div class=container> <input type=file id='id-face' name='face' accept=image/* /> <div id='face-empty-result'> <img style='width:4rem' src=https://github.com/wangheng3751/my-resources/blob/master/images/camera.png?raw=true <p >身分證正面照</p> </div> <img style='width: 100%' id='face-result'/> </div> <div class=container style='margin-top:0.5rem;'> <input type=file id='id-back' name='back' accept=image/* /> <div id='back-empty- result'> <img style='width:4rem' src=https://github.com/wangheng3751/my-resources/blob/master/images/camera.png?raw=true <p>身分證反面照</p> </div> <img style='width : 100%' id='back-result'/> </div> </div> </div> <div class=btn> 提交</div> </form> </body></html>2.創建index.css
body{ margin: 0}.content{ padding:0.5rem; display: flex; align-items: center; border-bottom: 1px #999 solid}.label{ width:5rem;}.img-area{ flex:1} .container{ background-color:#e7e7e7; position: relative;}.container div{ text-align: center; padding:0.5rem 0}.container input{ opacity:0; filter:alpha(opacity=0); height: 100%; width: 100%; position: absolute; top: 0; left: 0; ; z-index: 9;}.container p{ font-size: 0.9rem; color:#999}.btn{ background-color: #4363ab; color: #fff; text-align: center; padding: 0.5rem 1rem; width:80%; border-radius: 0.2rem; margin: 2rem auto; font border-radius: 0.2rem; margin: 2rem auto; font -weight: 600; font-size: 1.2rem} 3.創建index.js window.onload=function(){ document.getElementById(id-face).addEventListener(change, function(){ onFileChange(this,face-result,face-empty-result) }); document.getElementById(id-back) .addEventListener(change, function(){ onFileChange(this,back-result,back-empty-result) }); document.getElementsByClassName(btn)[0].addEventListener(click, function(){ submit(); });};/** * 選取圖片時的處理* @param {*} fileObj input file元素* @param {*} el //選取後用於顯示圖片的元素ID * @param {*} btnel //未選取圖片時顯示的按鈕區域ID */function onFileChange(fileObj,el,btnel){ var windowURL = window.URL || window.webkitURL; var dataURL; var imgObj = document.getElementByIdel( ); document.getElementById(btnel).style.display=none; imgObj.style.display=block; if (fileObj && fileObj.files && fileObj.files[0]) { dataURL = windowURL.createObjectURL(fileObj.files[0]); imgObj.src=dataURL: src .value; imgObj.style.filter = progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale); imgObj.filters.item(DXImageTransform.Microsoft.AlphaImageLoader).src = dataURL; }}/** * 將圖片壓縮後返回base64格式的資料* @param {* } image img元素* @param {*} width 壓縮後圖片寬度* @param {*} height 壓縮後圖片高度* @param {*} qua //圖片品質1-100 */function compressImageTobase64(image,width,height,qua){ var quality = qua ? qua / 100 : 0.8; var canvas = var ? document.createElement(canvas), ctx = canvas.getContext('2d'); var w = image.naturalWidth, h = image.naturalHeight; canvas.width = width||w; canvas.height = height||h; ctx.drawImage(image, 0, 0, w, h, 0, 0, width||w, height||h); var data = canvas.toDataURL(image/jpeg, quality); return data;}//提交function submit(){ //1、form提交//document.getElementById(mainForm).submit(); //2、壓縮後ajax提交var face_data=compressImageTobase64(document.getElementById(face-result),200,100,90); var back_data=compressImageTobase64(document.getElementById(back-result),200,100,90); var formData = new FormData(); formData.append(face,face_data); formData.append(back,backj_data); $.ajax({ url:/地址, type: 'POST', cache: false, data: formData, timeout:180000, processData: false, contentType: false, success:function(r){ }, error:function(r){ } });}原始碼： Github位址
總結以上所述是小編給大家介紹的html+css+js 實現拍照預覽上傳圖片功能，希望對大家有幫助，如果大家有任何疑問請給我留言，小編會及時回覆大家的。在此也非常感謝大家對VeVb武林網站的支持！