聊聊PHP中Base64 、Blob与File的相互转换方法

// 判断是否为base64格式字符串
function isBase64(str) {
    //正则表达式判断
    var reg = /^s*data:([a-z]+/[a-z0-9-+.]+(;[a-z-]+=[a-z0-9-]+)?)?(;base64)?,([a-z0-9!$&',()*+;=-._~:@/?%s]*?)s*$/i;
    return reg.test(str) //返回 true or false
}

console.log(data instanceof Blob)   //ture  or  false

console.log(data instanceof File && !data instanceof Blob)   //ture  or  false

function dataURLtoFile(dataurl, filename) {
    var arr = dataurl.split(','),
        mime = arr[0].match(/:(.*?);/)[1],
        bstr = atob(arr[1]),
        n = bstr.length,
        u8arr = new Uint8Array(n);
    while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
    }
    return new File([u8arr], filename, { type: mime });
}

function dataURLtoBlob(dataurl, filename) {
    var arr = dataurl.split(','),
        mime = arr[0].match(/:(.*?);/)[1],
        bstr = atob(arr[1]),
        n = bstr.length,
        u8arr = new Uint8Array(n);
    while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
    }
    return new Blob([u8arr], { type: mime });
}

function blobToFile(blob) {
    return new File([blob], 'screenshot.png', { type: 'image/jpeg' })
}