[JavaScript知识库]纯H5 app a标签下载图片

                const u = navigator.userAgent;
                let isIos = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/);
                if(isIos) {
                    const b64File = this.dataURL;
                    const contentType = b64File.substring(5, b64File.indexOf(';base64')) // 截取文件类型
                    const b64Data = b64File.substring(b64File.indexOf(',') + 1) // 获得文件头外的数据
                    const byteCharacters = atob(b64Data)
                    const byteNumbers = new Array(byteCharacters.length)
                    for (let i = 0; i < byteCharacters.length; i++) {
                        byteNumbers[i] = byteCharacters.charCodeAt(i)
                    }
                    const byteArray = new Uint8Array(byteNumbers)
                    const blob = new Blob([byteArray], {type: contentType})
                    const u = window.URL.createObjectURL(blob) // 获得的链接
                    location.href = u;
                } else {
                    const hideDownload = document.createElement('a');
                    hideDownload.href = this.dataURL;
                    hideDownload.download = '快照';
                    hideDownload.target = '_blank';
                    hideDownload.click();
                    hideDownload.remove();
                }