1

20220330_Vote/Ewide.Web.Entry/wwwroot/lib/xe-utils/reduce.js

@@ -0,0 +1,39 @@
+var keys = require('./keys')
+
+/**
+  * 接收一个函数作为累加器，数组中的每个值（从左到右）开始合并，最终为一个值。
+  *
+  * @param {Array} array 数组
+  * @param {Function} callback 方法
+  * @param {Object} initialValue 初始值
+  * @return {Number}
+  */
+function reduce (array, callback, initialValue) {
+  if (array) {
+    var len, reduceMethod
+    var index = 0
+    var context = null
+    var previous = initialValue
+    var isInitialVal = arguments.length > 2
+    var keyList = keys(array)
+    if (array.length && array.reduce) {
+      reduceMethod = function () {
+        return callback.apply(context, arguments)
+      }
+      if (isInitialVal) {
+        return array.reduce(reduceMethod, previous)
+      }
+      return array.reduce(reduceMethod)
+    }
+    if (isInitialVal) {
+      index = 1
+      previous = array[keyList[0]]
+    }
+    for (len = keyList.length; index < len; index++) {
+      previous = callback.call(context, previous, array[keyList[index]], index, array)
+    }
+    return previous
+  }
+}
+
+module.exports = reduce