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

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+var isArray = require('./isArray')
+
+/**
+  * 浅复制数组的一部分到同一数组中的另一个位置,数组大小不变
+  *
+  * @param {Array} array 数组
+  * @param {Number} target 从该位置开始替换数据
+  * @param {Number} start 从该位置开始读取数据，默认为 0 。如果为负值，表示倒数
+  * @param {Number} end 到该位置前停止读取数据，默认等于数组长度。如果为负值，表示倒数
+  * @return {Array}
+  */
+function copyWithin (array, target, start, end) {
+  if (isArray(array) && array.copyWithin) {
+    return array.copyWithin(target, start, end)
+  }
+  var replaceIndex, replaceArray
+  var targetIndex = target >> 0
+  var startIndex = start >> 0
+  var len = array.length
+  var endIndex = arguments.length > 3 ? end >> 0 : len
+  if (targetIndex < len) {
+    targetIndex = targetIndex >= 0 ? targetIndex : len + targetIndex
+    if (targetIndex >= 0) {
+      startIndex = startIndex >= 0 ? startIndex : len + startIndex
+      endIndex = endIndex >= 0 ? endIndex : len + endIndex
+      if (startIndex < endIndex) {
+        for (replaceIndex = 0, replaceArray = array.slice(startIndex, endIndex); targetIndex < len; targetIndex++) {
+          if (replaceArray.length <= replaceIndex) {
+            break
+          }
+          array[targetIndex] = replaceArray[replaceIndex++]
+        }
+      }
+    }
+  }
+  return array
+}
+
+module.exports = copyWithin