JavaScript Array And Object Methods.pdf

Arrays:
- Creation: `const arr = ['Laurence', 4, 5, 5, 5, 6, 'Svekis'];` or `const arr1 = new Array('Laurence', 'Svekis');`
- Accessing Elements: `console.log(arr[1]);` or `console.log(arr1[0]);`
- Length: `console.log(arr.length);`
- Last Element: `console.log(arr[arr.length - 1]);`
- Nested Arrays: Loop through inner arrays using nested loops: `for (let x = 0; x < arr[i].length; x++) { console.log(arr[i][x]); }`
- Array Static Methods:
- `Array.from()`: Create an array from an array-like or iterable object. `const arr = Array.from(str);`
- `Array.of()`: Create a new array with specified elements. `const arr4 = Array.of(5);`
- `Array.isArray()`: Check if an object is an array. `console.log(Array.isArray(arr));`
- Array Update Methods:
- `arr.push(...)`: Add elements to the end of an array. `arr.push(10);`
- `arr.pop()`: Remove and return the last element of an array. `const popped = arr.pop();`
- `arr.shift()`: Remove and return the first element of an array. `const shifted = arr.shift();`
- `arr.unshift(...)`: Add elements to the beginning of an array. `arr.unshift(1, 2);`
- `arr.splice(index, deleteCount, ...items)`: Change content by removing or replacing existing elements and/or adding new elements in place. `arr.splice(2, 2, 'new', 'element');`
- Array Filter Methods:
- `arr.filter(callback)`: Create a new array with all elements that pass the test implemented by the provided function. `const filtered = arr.filter(ele => ele > 5);`
- `arr.includes(searchElement, fromIndex)`: Determine whether an array includes a certain value among its entries, returning `true` if it does, `false` otherwise. `console.log(arr.includes(5));`
- Array Map Method: Create a new array with the results of calling a provided function on every element in the calling array. `const mapped = arr.map(ele => ele * 2);`
- Array Reduce Method: Execute a reducer function (that you provide) on each element of the array, resulting in a single output value. `const sum = arr.reduce((acc, ele) => acc + ele, 0);`
- Array Sort Method: Sort the elements of an array in place and returns the array. `arr.sort((a, b) => b - a);`
- Array Iteration: Use `for...of` loop to iterate over array elements. `for (const ele of arr) { console.log(ele); }`

Objects:
- Creation: `const obj = { first: 'Laurence', last: 'Svekis' };` or `const obj1 = new Object(); obj1.first = 'Laurence'; obj1.last = 'Svekis';`
- Object Static Methods:
- `Object.assign(target, ...sources)`: Copies the values of all enumerable own properties from one or more source objects to a target object. `const obj2 = Object.assign({}, obj, { middle: 'S' });`
- `Object.keys(obj)`: Returns an array of a given object's own enumerable string-keyed property names. `console.log(Object.keys(obj));`
- `Object.values(obj)`: Returns an array of a given object's own enumerable value-keyed property values. `console.log(Object.values(obj));`
- `Object.entries(obj)`: Returns an array of a given object's own enumerable string-keyed property [key, value] pairs. `console.log(Object.entries(obj));`
- Object Iteration: Use `for...in` loop to iterate over object properties. `for (const prop in obj) { console.log(`${prop}: ${obj[prop]}`); }`
- Object Cloning: Use `Object.assign()` or spread operator (`{ ...obj }`) to create a shallow copy of an object. `const clone = { ...obj };`
- Object Deep Cloning: Use `JSON.parse(JSON.stringify(obj))` to create a deep copy of an object. `const deepClone = JSON.parse(JSON.stringify(obj));`