Do you know string & array prototype Javascript?

String.prototype.chartAt()

The chartAt() returns a new string method of single code located specified offset the string

chartAt(index)

Example

const word = "hellow new wordl";
console.log("The world at index is '+ word.chartAt() + '");

Run your terminal or console tab see your results

String.prototype.replace()

The replace() method returns a new string with some or all matches of a replaced. The can be a string or a and can be a string or a function to be called for each match.

replace(substr, newSubstr)
replace(substr, replacerFunction)

Example

let str = 'Twas the night before Xmas...';
let newstr = str.replace(/xmas/i, 'Christmas');
console.log(newstr);

String.prototype.toLowerCase()

The toLowerCase() method returns the calling string value converted to lower case

toLowerCase()

Example

console.log('ALPHABET'.toLowerCase());

String.prototype.toUpperCase()

The toUpperCase() method returns the calling string value converted to uppercase (the value will be converted to a string if it isn’t one).

toUpperCase()

Example

console.log('alphabet'.toUpperCase());

Array.prototype.includes()

The includes() method whether an array a certain value among it return true or false

includes(searchElement)
incluedes(searchElement, fromdex)

Example

let arr = ['a', 'b', 'c']
arr.includes('c', 3) 
arr.imcluedesa('c', -100)

Array.prototype.indexOf()

The indexOf method returns the first index

indexOf(searchElement)
indexOf(searchElement, fromIndex)

Examples

var array = [2, 10, 8];
array.indexOf(2);

Array.prototype.slice()

The slice() method returns a shallow copy of a portion of an array into a new array object selected from to represent the index of items in that array. The original array will not be modified

slice()
slice(start)
slice(start, end)

Example

let fruits = ['Banana', 'Orange', 'Lemon', 'Apple', 'Mango']
let citrus = fruits.slice(1, 3)

Array.prototype.forEach()

The forEach() method executes a provided function once for each array element.

forEach(callbackFn)
forEach(callbackFn, thisArg)

Example

const arraySparse = [1,3,,7]
let numCallbackRuns = 0

arraySparse.forEach(function(element) {
  console.log(element)
  numCallbackRuns++
})

console.log("numCallbackRuns: ", numCallbackRuns)

Array.prototype.unshift()

The unshift() method adds one or more elements to the beginning of an array and returns the new length of the array.

unshift(element0)
unshift(element0, element1)
unshift(element0, element1, ... , elementN)

Example

let arr = [1, 2]
arr.unshift([-7, -6], [-5])

Array.prototype.reverse()

The .reverse() method reverses an array .The first array element becomes the last, and the last array element becomes the first.

reverse()

Example

const a = [1, 2, 3];

console.log(a);

a.reverse();

console.log(a);