refactor(upload): 简化 #1919 (#1974)

docs/upload/detail/options.md

@@ -389,35 +389,36 @@ before: function(obj){ // obj 参数同 choose
   */
 }
 
-// 返回 jQuery Deferred.promise 对象或 JS 原生 Promise 对象，reject 表明阻止上传(2.9.11+)
+// 返回 jQuery Deferred 对象或 JS 原生 Promise 对象，false 或 Promise.reject 表明阻止上传(2.9.11+)
 // Promise
+/** @type {(obj: object) => boolean | JQueryDeferred<boolean> | Promise<boolean>} */
 before: function(obj){
   return new Promise(function(resolve, reject){
     setTimeout(function(){
       console.log('before_async_task', obj);
-      resolve();
+      resolve(true);
     }, 1000)
   })
 }
 
 // Deferred
 before: function(obj){
-  return $.Deferred(function(deferred){
+  return $.Deferred(function(defer){
     setTimeout(function(){
       console.log('before_async_task', obj);
-      deferred.resolve();
+      defer.resolve(true);
     }, 1000)
   }).promise();
 }
 
 // Deferred2
 before: function(obj){
-  var deferred = $.Deferred();
+  var defer = $.Deferred();
   setTimeout(function(){
     console.log('before_async_task', obj);
-    deferred.resolve();
+    defer.resolve(true);
   }, 1000)
-  return deferred.promise();
+  return defer.promise();
 }
 ```
 

src/modules/upload.js

@@ -471,20 +471,14 @@ layui.define(['lay', 'layer'], function(exports){
       }
       // 上传前的回调 - 如果回调函数明确返回 false 或 Promise.reject，则停止上传
       if(typeof options.before === 'function'){
-        var maybePromise = options.before(args);
+        upload.util.promiseLikeResolve(options.before(args))
-        if(maybePromise === false){
+          .then(function(result){
-          return;
+            if(result !== false){
-        }else if(typeof maybePromise === 'object' && typeof maybePromise.then === 'function'){
-          // 兼容 jQuery Deferred Promise 对象和原生 Promise 对象
-          // 类型检测不够完善，但足以满足此场景
-          maybePromise.then(function(result){
-            ready();
-          }, function(error){
-            layui.hint().error(error);
-          })
-        }else{
               ready();
             }
+          }, function(error){
+            error !== undefined && layui.hint().error(error);
+          })
       }else{
         ready();
       }
@@ -781,6 +775,19 @@ layui.define(['lay', 'layer'], function(exports){
       size = formatSize / Math.pow(1024, index);
       size = size % 1 === 0 ? size : parseFloat(size.toFixed(precision));//保留的小数位数
       return size + unitArr[index];
+    },
+    /**
+     * 将给定的值转换为一个 JQueryDeferred 对象
+     */
+    promiseLikeResolve:function(value){
+      var deferred = $.Deferred();
+
+      if(value && typeof value.then === 'function'){
+        value.then(deferred.resolve, deferred.reject);
+      }else{
+        deferred.resolve(value);
+      }
+      return deferred.promise();
     }
   }