本地图片生成base64

/**
 * @description: 获取本地图片base64
 * @param {Object} file blob [input:file].files[0]
 * @return { String }  base64
 */
getLocalFileBase64 = file => {
    return new Promise((resolve, reject) => {
        const fileReadr = new FileReader()
        fileReadr.readAsDataURL(file)
        fileReadr.onload = function(params) {
            resolve(params.target.result)
        }
        fileReadr.onerror = function(params) {
            reject(params)
        }
    })
}