添加读取文件函数

src/assets/js/utils.js

@@ -30,17 +30,73 @@ class Utils {
                 console.log('[JSONP]', data);
             },
         };
-        var scriptElem = document.createElement('script');
+        var el = document.createElement('script');
 
         Object.assign(config, options);
         window[config.cbName] = config.cbFunc;
 
-        scriptElem.addEventListener('load', function () {
+        el.addEventListener('load', function () {
             this.remove();
         });
-        scriptElem.setAttribute('src', config.url);
+        el.setAttribute('src', config.url);
 
-        document.body.appendChild(scriptElem);
+        document.body.appendChild(el);
+    }
+
+    /**
+     * 以文本方式读取文件（异步）
+     * 
+     * @param {Event} ev 输入框 change 事件对象
+     * @param {boolean} resetValue 是否自动重置输入框 value 属性
+     * 
+     * @returns {Promise<string[]>} `{ name: 文件名, content: 文件内容 }`
+     */
+    readFileAsText(ev, resetValue) {
+        const blank = [];
+
+        /** @type {HTMLInputElement} */
+        const el = ev.currentTarget;
+
+        /** @type {FileList} */
+        const files = el.files;
+
+        if (!files || files.length === 0) {
+            return Promise.resolve(blank);
+        }
+
+        const fnProc = (procResolve, procReject) => {
+            const reads = [];
+
+            for (let i = 0; i < files.length; i++) {
+                const file = files[i];
+                const reader = new FileReader();
+                const fnRead = (readResolve, readReject) => {
+                    // 成功
+                    reader.onload = () => {
+                        readResolve(reader.result);
+                    };
+                    // 失败
+                    reader.onerror = () => {
+                        readReject('');
+                    };
+                    // 读取
+                    reader.readAsText(file);
+                };
+
+                reads.push(new Promise(fnRead));
+            }
+
+            Promise.all(reads).then((res) => {
+                // [成功]
+                procResolve(res);
+                resetValue && el.setAttribute('value', '');
+            }).catch(() => {
+                // [失败]
+                procReject(blank);
+            });
+        };
+
+        return new Promise(fnProc);
     }
 
 }