前端JS识别二维码内容

原文：https://www.cnblogs.com/houxianzhou/p/15030351.html

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<html><head><meta charset="utf-8" /><title>图片二维码识别</title><script src="https://cdn.bootcss.com/jquery/3.4.1/jquery.min.js"></script><script src="https://cozmo.github.io/jsQR/jsQR.js"></script></head><body><span lan_id="bc">选择图片</span> <input type="file"  id="pictureChange"/><div><h2>识别结果：</h2><ul id="result"></ul></div></body><script type="text/javascript">$("body").append('<canvas id="qrcanvas" style="display:none;"></canvas>')$("#pictureChange").change(function (e) {var file = e.target.files[0];if(window.FileReader) {var fr = new FileReader();fr.readAsDataURL(file);fr.onloadend = function(e) {var base64Data = e.target.result;base64ToqR(base64Data)}}})function base64ToqR(data) {var c = document.getElementById("qrcanvas");var ctx = c.getContext("2d");var img = new Image();img.src = data;img.onload = function() {$("#qrcanvas").attr("width",img.width)$("#qrcanvas").attr("height",img.height)ctx.drawImage(img, 0, 0, img.width, img.height);var imageData = ctx.getImageData(0, 0, img.width, img.height);const code = jsQR(imageData.data, imageData.width, imageData.height, {inversionAttempts: "dontInvert",});if(code){showCode(code.data)}else{alert("识别错误")}};}function showCode(code){$("#result").append("<li>"+code+"</li>")}</script>
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