同源(访问的网站域名与服务器域名一致)才能用方法一下载

方法一： 同源资源文件下载

const downLoadFunc = (imgSrc, imgName) => {
       if (!imgSrc)  return
        let url = window.URL.createObjectURL(new Blob([imgSrc]))
        let link = document.createElement('a')
        link.style.display = 'none'
        link.href = url
        link.setAttribute('download', imgName)
        document.body.appendChild(link)
        link.click()
}

方法二： 跨域资源图片下载

const downLoadFunc = (imgSrc, imgName) => {
        if (!imgSrc)  return
        let image = new Image() 
        image.setAttribute('crossOrigin', 'anonymous')
        image.onload = function () {
            let canvas = document.createElement('canvas')
            canvas.width = image.width
            canvas.height = image.height
            let context = canvas.getContext('2d')
            context.drawImage(image, 0, 0, image.width, image.height)
            let url = canvas.toDataURL('image/png') //得到图片的base64编码数据

            let link = document.createElement('a') 
            let event = new MouseEvent('click') 
            link.download = imgName || (new Date().getTime())  
            link.href = url  
            link.dispatchEvent(event)  
        }
        image.src = imgSrc
}

方法三： 跨域资源pdf下载

const downLoadFunc = (imgSrc, imgName) => { 
        if (!imgSrc)  return
        fetch(imgSrc).then(function (response) {
            response.arrayBuffer().then(res => {
                let type = 'application/pdf;charset-UTF-8' // 资源类型pdf
                // 常见资源类型 
                   // 1.excel: type = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
                   // 2.图片: type = "image/*"
                   // 3.视频: type = "video/*"
                   // 4.音频: type = "audio/*"
                   // 5.pdf: type = "application/pdf;charset-UTF-8"
                //
                let blob = new Blob([res], {type: type})
                let objectUrl = URL.createObjectURL(blob)
                let link = document.createElement('a')
                link.style.display = 'none'
                link.href = objectUrl
                link.setAttribute('download', imgName)
                document.body.appendChild(link)
                link.click()
                document.body.removeChild(link)
            })
        })
}