René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"移动元素函数里 判断over\u003c0的情况 i应该从startIdx+delCount+over开始","articleBody":"```js\r\n移动元素函数里 判断over\u003c0的情况 i应该从startIdx+delCount+over开始\r\n/**\r\n数组splice方法实现\r\n\r\narr.splice(startIdx,delCount,add1,add2,...);\r\n*/\r\nArray.prototype._splice = function () {\r\n//1. 记录入参个数\r\nlet argumentsLen = arguments.length;\r\nlet start = arguments[0], deleteCount = arguments[1];\r\n//2. 数组长度\r\nlet arrayLength = this.length;\r\nlet arr = Object(this);\r\n//3. 添加元素个数\r\nlet addCount = argumentsLen \u003e 2 ? argumentsLen - 2 : 0\r\nconsole.log('addCount: ', addCount);\r\n//4. 计算有效的开始位置start\r\nlet startIdx = computeSpliceStartIdx(start, arrayLength);\r\n//5. 计算有效的删除个数\r\nlet delCount = computeSpiceDelCount(startIdx, deleteCount, arrayLength);\r\n\r\nconsole.log('delCount: ', delCount);\r\n//6. 记录删除的元素\r\nlet delElements = new Array(delCount);\r\nrecordDelElements(startIdx, delCount, arr, delElements);\r\n//7. 判断是否是密封对象\r\nif (delCount !== addCount \u0026\u0026 Object.isSealed(arr)) {\r\nthrow new TypeError('the arr is sealed')\r\n}\r\n//8. 判断是否是冻结对象\r\nif (delCount \u003e 0 \u0026\u0026 addCount \u003e 0 \u0026\u0026 Object.isFrozen(arr)) {\r\nthrow new TypeError('the arr is frozen')\r\n}\r\n//移动数组元素\r\nmoveElements(startIdx, delCount, arr, addCount);\r\nlet i = startIdx;\r\nlet argumentsIdx = 2;\r\n//插入新的元素\r\nwhile (argumentsIdx \u003c argumentsLen) {\r\narr[i++] = arguments[argumentsIdx++];\r\n}\r\narr.length = arrayLength - delCount + addCount;\r\nreturn delElements;\r\n}\r\nfunction computeSpliceStartIdx(start, arrayLength) {\r\nif (start \u003c 0) {\r\nstart += arrayLength;\r\nreturn start \u003c 0 ? 0 : start;\r\n}\r\n//start\u003e0的情况\r\nreturn start \u003e arrayLength - 1 ? arrayLength - 1 : start;\r\n}\r\n//计算delCount\r\nfunction computeSpiceDelCount(startIdx, deleteCount, arrayLength) {\r\nif (deleteCount \u003e arrayLength - startIdx) {\r\ndeleteCount = arrayLength - startIdx\r\n}\r\nif (deleteCount \u003c 0) deleteCount = 0\r\nreturn deleteCount;\r\n}\r\n//记录删除的元素\r\nfunction recordDelElements(startIdx,delCount,arr,delElements) {\r\nfor(let i=0;i\u003cdelCount;i++) {\r\ndelElements[i] = arr[startIdx+i];\r\n}\r\n}\r\n//移动数组\r\nfunction moveElements(startIdx, delCount, arr, addCount){\r\nlet over = addCount - delCount;\r\nconsole.log('over: ', over);\r\nif(over\u003e0) {\r\n//增加的数大于了删除的数 向后移动\r\nfor(let i=arr.length-1;i\u003e=startIdx+delCount;i--) {\r\narr[i+over] = arr[i];\r\n}\r\n} else if(over\u003c0) {\r\n//增加的数小于删除的数 向前移动\r\nfor(let i=startIdx+delCount+over;i\u003c=arr.length-1;i++) {\r\nif(i+Math.abs(over)\u003earr.length-1) {\r\ndelete arr[i]\r\ncontinue\r\n}\r\narr[i] = arr[i+Math.abs(over)];\r\n}\r\nconsole.log('arr: over\u003c0', arr);\r\n}\r\n}\r\nlet arr = [1, 2, 3, 4, 5];\r\narr._splice(1,3,6,7)\r\nconsole.log('arr: ', arr);//arr: [ 1, 6, 7, 5 ]\r\n```\r\n\r\n_Originally posted by @xllpiupiu in https://github.com/sisterAn/JavaScript-Algorithms/issues/138#issuecomment-932177874_","author":{"url":"https://github.com/xllpiupiu","@type":"Person","name":"xllpiupiu"},"datePublished":"2021-10-01T12:20:18.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/168/JavaScript-Algorithms/issues/168"}