Javascript 使用Fetch-In-js下载图像

我正在尝试使用fetch-in-js下载一个图像。但每当我调用函数时，我都会面临CORS错误

            var image_trade_license = new Image();
            image_trade_license.crossOrigin = "anonymous";
            image_trade_license.src = "https://via.placeholder.com/150/92c952";
            // get file name - you might need to modify this if your image url doesn't contain a file extension otherwise you can set the file name manually
            var fileName_trade_license = 'trade_license';
            image_trade_license.onload = function () {
                var canvas = document.createElement('canvas');
                canvas.width = this.naturalWidth; // or 'width' if you want a special/scaled size
                canvas.height = this.naturalHeight; // or 'height' if you want a special/scaled size
                canvas.getContext('2d').drawImage(this, 0, 0);
                var blob_trade_license;
                // ... get as Data URI
                if (image_trade_license.src.indexOf(".jpg") > -1) {
                blob_trade_license = canvas.toDataURL("image_trade_license/jpeg");
                } else if (image_trade_license.src.indexOf(".png") > -1) {
                blob_trade_license = canvas.toDataURL("image_trade_license/png");
                } else if (image_trade_license.src.indexOf(".gif") > -1) {
                blob_trade_license = canvas.toDataURL("image_trade_license/gif");
                } else {
                blob_trade_license = canvas.toDataURL("image_trade_license/png");
                }
                $("#image1").append("<a download='" + fileName_trade_license + "' href='" + blob_trade_license + "'><button>Download Trade License</button></a>");
            }

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首先，您是否在fetch config中设置过

模式：“no cors”

？像这样：

fetch('https://via.placeholder.com/150/92c952', {
      method: 'POST',
      mode: "no-cors"
})

如果您仍然收到CORS错误。您可以在Chrome中禁用源策略以继续调用API，而不会出现CORS错误

---

或者，可以在Web浏览器中为您提供有关CORS的更多信息

参考这个答案，试着这样做

fetch（'https://via.placeholder.com/150/92c952“，{method:'GET'，mode:'no cors'}）。然后（resp=>console.log（'test'））

cors错误通常是后端的问题。请让后端开发人员插入cors代码。对于express.js后端，您可以参考以下页面：@AlekseiBulgak我尝试了这个，但仍然没有得到正确的输出。

fetch('https://via.placeholder.com/150/92c952', {
      method: 'POST',
      mode: "no-cors"
})