vue项目开发时需要将选择的文件转为base64编码上传，所以需要在el-upload选择文件后，将其转为base64编码

html

<el-upload action="#" :on-change="handleChangeUpload" list-type="picture-card" :auto-upload="false">
	<i class="el-icon-plus"></i>
</el-upload>

js

handleChangeUpload(file, fileList) {
                this.getBase64(file.raw).then(res => {
                    console.log(res)
                });
            },
            getBase64(file) {
                return new Promise(function(resolve, reject) {
                    let reader = new FileReader();
                    let imgResult = "";
                    reader.readAsDataURL(file);
                    reader.onload = function() {
                        imgResult = reader.result;
                    };
                    reader.onerror = function(error) {
                        reject(error);
                    };
                    reader.onloadend = function() {
                        resolve(imgResult);
                    };
                });
            },