All about JavaScript and its syntax and other cool stuff Learning it at fastest speed I can so that I can move to React (big boy stuff)
/ STRING // string[index] - get a certain character of a string // string.length - return the number of characters in a string // string.split(' ') - returns an array of words of a string // string.split('') - returns an array of characters of a string // string.toLowerCase() - returns a lowercased string // string.toUpperCase() - returns an uppercased string // string.includes('subtring') - checks whether a substring exists inside of a string [check the characther case]
// ARRAY // array[index] - returns a certain value from an array // array.indexOf('value') - returns the index of the first occurance of that value // array.length - returns the number of elements in the array // array.join('') - returns a string of array values // array.push(value) - adds the value to the end of the array // array.pop() - removes the value from the end of the array // array.unshift(value) - adds the value to the start of the array // array.shift() - removes the value from the start of the array // array.splice(fromIndex, number_of_elements) - removes the number_of_elements, starting from fromIndex from the array // array.slice(fromIndex, toIndex) - copies a certain part of the array
// for - looping const emojis = [ '😀', '😆', '🙃', '😍' ]; const wavingEmojis = [];
for (let i = 0; i < emojis.length; i++) {
wavingEmojis.push(👋${emojis[i]}👋);
}
// forEach - array method for looping emojis.forEach((emoji) => console.log(emoji));
// map - array method for looping BUT IT HAS RETURNS
const wavingEmojis = emojis.map((emoji) => 👋${emoji}👋);
// filter const numbers = [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ];
const numbersBiggerThanFive = numbers.filter((number) => number > 5);
// sort const numbers = [ 3, 4, 1, 5, 4, 7, 2, 23, 12 ];
const sortFromSmalles = numbers.sort((a, b) => a - b); const sortFromLargest = numbers.sort((a, b) => b - a);
// VALUE VS REFERENCE (part 1: intro) // arrays const numbers = [ 1, 2, 3, 4 ]; // #123asd const anotherNumbers = numbers; // #123asd
anotherNumbers.push(5);
// objects const person = { firstName: 'John', lastName: 'Doe' };
const anotherPerson = person;
anotherPerson.lastName = 'DOEEEE';
console.log(numbers === anotherNumbers); // true console.log(person === anotherPerson) // true
// VALUE VS REFERENCE (part 2: CLONING ARRAYS AND OBJECTS) // SHALLOW CLONING - ONE LEVEL DEEP const original = [ 1, 2, 3 ]; const newOriginal = [...original];
// DEEP CLONING - TWO LEVELS DEEP const users = [ { name: 'John', age: 25 }, { name: 'Victor', age: 25 }, { name: 'Adrian', age: 25 } ]; const newUsers = JSON.parse(JSON.stringify(users));