이 게시물의 모든 코드는 repo Github에서 확인하실 수 있습니다.
/** * @param {number} index * @return {any | undefiend} */ Array.prototype.myAt = function (index) { const len = this.length; if (index < -len || index >= len) { return; } return this[(index + len) % len]; }; // Usage example console.log([1, 2, 3, 4].myAt(2)); // => 3 console.log([1, 2, 3, 4].myAt(-1)); // => 4 console.log([1, 2, 3, 4].myAt(5)); // => undefined
/** * @template T * @param {...(T | Array<T>)} itemes * @return {Array<T>} */ Array.prototype.myConcat = function (...items) { const newArray = [...this]; for (const item of items) { if (Array.isArray(item)) { newArray.push(...item); } else { newArray.push(item); } } return newArray; }; // Usage example console.log([1, 2, 3].myConcat([])); // => [1, 2, 3]; console.log([1, 2, 3].myConcat([4, 5, 6, [2]])); // => [1, 2, 3, 4, 5, 6, [2]];
/** * @template T * @param { (value: T, index: number, array: Array<T>) => boolean } callbackFn * @param {any} [thisArg] * @return {boolean} */ Array.prototype.myEvery = function (callbackFn, thisArg) { const len = this.length; let flag = true; for (let i = 0; i < len; i += 1) { if (Object.hasOwn(this, i) && !callbackFn.call(thisArg, this[i], i, this)) { flag = false; break; } } return flag; }; // Usage example console.log([1, 2, 3].myEvery((item) => item > 2)); // => false console.log([1, 2, 3].myEvery((item) => item > 0)); // => true
/** * @template T, U * @param { (value: T, index: number, array: Array<T>) => boolean } callbackFn * @param { any } [thisArg] * @return {Array<T>} */ Array.prototype.myFilter = function (callbackFn, thisArg) { const newArray = []; for (let i = 0; i < this.length; i += 1) { if (Object.hasOwn(this, i) && callbackFn.call(thisArg, this[i], i, this)) { newArray.push(this[i]); } } return newArray; }; // Usage example console.log([1, 2, 3, 4].myFilter((value) => value % 2 == 0)); // => [2, 4] console.log([1, 2, 3, 4].myFilter((value) => value < 3)); // => [1, 2]
/** * @param { Array } arr * @param { number } depth * @returns { Array } */ function flatten(arr, depth = 1) { const newArray = []; for (let i = 0; i < arr.length; i += 1) { if (Array.isArray(arr[i]) && depth !== 0) { newArray.push(...flatten(arr[i], depth - 1)); } else { newArray.push(arr[i]); } } return newArray; } // Usage example const words = ["spray", "elite", "exuberant", "destruction", "present"]; const result = words.filter((word) => word.length > 6); console.log(result); // => ["exuberant", "destruction", "present"]
/** * @template T, U * @param { (value: T, index: number, array: Array<T>) => U } callbackFn * @param {any} [thisArg] * @return {Array<U>} */ Array.prototype.myForEach = function (callbackFn, thisArg) { if (this == null) { throw new TypeError("this is null or not defined"); } if (typeof callbackFn !== "function") { throw new TypeError(callbackFn + " is not a function"); } const O = Object(this); // Zero-fill Right Shift to ensure that the result if always non-negative. const len = O.length >>> 0; for (let i = 0; i < len; i += 1) { if (Object.hasOwn(O, i)) { callbackFn.call(thisArg, O[i], i, O); } } }; // Usage example console.log( [1, 2, 3].myForEach((el) => el * el), null ); // => [1, 4, 9];
/** * @param {any} searchElement * @param {number} fromIndex * @return {number} */ Array.prototype.myIndexOf = function (searchElement, fromIndex = 0) { const len = this.length; if (fromIndex < 0) { fromIndex = Math.max(0, fromIndex + this.length); } for (let i = fromIndex; i < len; i += 1) { if (this[i] === searchElement) { return i; } } return -1; } // Usage example console.log([1, 2, 3, 4, 5].myIndexOf(3)); // => 2 console.log([1, 2, 3, 4, 5].myIndexOf(6)); // => -1 console.log([1, 2, 3, 4, 5].myIndexOf(1)); // => 0 console.log(['a', 'b', 'c'].myIndexOf('b')); // => 1 console.log([NaN].myIndexOf(NaN)); // => -1 (since NaN !== NaN)
/** * @return {null|boolean|number|string|Array|Object} */ Array.prototype.myLast = function () { return this.length ? this.at(-1) : -1; }; // Usage example console.log([].myLast()); // => -1; console.log([1].myLast()); // => 1 console.log([1, 2].myLast()); // => 2
/** * @template T, U * @param { (value: T, index: number, array: Array<T>) => U } callbackFn * @param {any} [thisArg] * @return {Array<U>} */ Array.prototype.myMap = function (callbackFn, thisArg) { const len = this.length; const newArray = Array.from({ length: len }); for (let i = 0; i < len; i += 1) { if (Object.hasOwn(this, i)) { newArray[i] = callbackFn.call(thisArg, this[i], i, this); } } return newArray; }; // Usage example console.log([1, 2, 3, 4].myMap((i) => i)); // => [1, 2, 3, 4] console.log([1, 2, 3, 4].myMap((i) => i * i)); // => [1, 4, 9, 16])
/** * @template T, U * @param { (previousValue: U, currentValue: T, currentIndex: number, array: Array<T>) => U } callbackFn * @param {U} [initialValue] * @return {U} */ Array.prototype.myReduce = function (callbackFn, initialValue) { const hasInitialValue = initialValue !== undefined; const len = this.length; if (!hasInitialValue && !len) { throw new Error("Reduce of empty array with no initial value"); } let accumulator = hasInitialValue ? initialValue : this[0]; let startingIndex = hasInitialValue ? 0 : 1; for (let i = startingIndex; i < len; i += 1) { if (Object.hasOwn(this, i)) { accumulator = callbackFn(accumulator, this[i], i, this); } } return accumulator; }; // Usage example const numbers = [1, 2, 3, 4, 5]; const sum = numbers.myReduce((acc, num) => acc + num, 0); console.log(sum); // => 15 const products = numbers.myReduce((acc, num) => acc * num, 1);
/** * @template T * @param { (value: T, index: number, array: Array<T>) => boolean } callbackFn * @param {any} [thisArg] * @return {boolean} */ Array.prototype.mySome = function (callbackFn, thisArg) { const len = this.length; let flag = false; for (let i = 0; i < len; i += 1) { if (Object.hasOwn(this, i) && callbackFn.call(thisArg, this[i], i, this)) { flag = true; break; } } return flag; }; // Usage example console.log([1, 2, 3].mySome((item) => item > 2)); // => true console.log([1, 2, 3].mySome((item) => item < 0)); // => false
/** * @return {Array<number>} */ Array.prototype.mySquare = function () { const len = this.length; const newArray = Array.from({ length: len }); for (let i = 0; i < len; i += 1) { newArray[i] = this[i] * this[i]; } return newArray; }; // Usage example console.log([1, 2, 3].mySquare()); // => [1, 4, 9]; console.log([].mySquare()); // => [];
위 내용은 배열 프로토타입 - JavaScript 과제의 상세 내용입니다. 자세한 내용은 PHP 중국어 웹사이트의 기타 관련 기사를 참조하세요!