Home > Web Front-end > JS Tutorial > body text

JavaScript Cheat Sheets

王林
Release: 2024-08-08 03:41:12
Original
1196 people have browsed it

JavaScript Cheat Sheets

Hey everyone! I've got some great news for all you beginners learning JavaScript! A quick reference guide for JavaScript is now available! You can easily check important concepts, functions, and methods right away. For more details about the guide, check it out here.

What's in the Quick Reference Guide

Console

// => Hello world!
console.log("Hello world!");

// => Hello CheatSheets.zip
console.warn("hello %s", "CheatSheets.zip");

// Output error message to standard error
console.error(new Error("Oops!"));
Copy after login

Numbers

let amount = 6;
let price = 4.99;
Copy after login

Variables

let x = null;
let name = "Tammy";
const found = false;

// => Tammy, false, null
console.log(name, found, x);

var a;
console.log(a); // => undefined
Copy after login

Strings

let single = "Wheres my bandit hat?";
let double = "Wheres my bandit hat?";

// => 21
console.log(single.length);
Copy after login

Arithmetic Operators

5 + 5 = 10     // Addition
10 - 5 = 5     // Subtraction
5 * 10 = 50    // Multiplication
10 / 5 = 2     // Division
10 % 5 = 0     // Modulus
Copy after login

Comments

// This is a comment

/*
You need to change this setting
before deployment.
*/
Copy after login

Assignment Operators

let number = 100;

// Both statements add 10
number = number + 10;
number += 10;

console.log(number);
// => 120
Copy after login

String Interpolation

let age = 7;

// String concatenation
"Tommy is " + age + " years old.";

// String interpolation
`Tommy is ${age} years old.`;
Copy after login

Conditional Statements

const isMailSent = true;

if (isMailSent) {
  console.log("Mail sent to recipient");
}
Copy after login

Ternary Operator

var x = 1;

// => true
result = x == 1 ? true : false;
Copy after login

Logical Operators

true || false; // true
10 > 5 || 10 > 20; // true
false || false; // false
10 > 100 || 10 > 20; // false
Copy after login

Comparison Operators

1 > 3; // false
3 > 1; // true
250 >= 250; // true
1 === 1; // true
1 === 2; // false
1 === "1"; // false
Copy after login

Arrays

const fruits = ["apple", "orange", "banana"];

// Different data types
const data = [1, "chicken", false];
Copy after login

Objects

const apple = {
  color: "Green",
  price: { bulk: "$3/kg", smallQty: "$4/kg" },
};
console.log(apple.color); // => Green
console.log(apple.price.bulk); // => $3/kg
Copy after login

Classes

class Dog {
  constructor(name) {
    this._name = name;
  }

  introduce() {
    console.log("This is " + this._name + " !");
  }

  // Static method
  static bark() {
    console.log("Woof!");
  }
}

const myDog = new Dog("Buster");
myDog.introduce();

// Calling static method
Dog.bark();
Copy after login

Modules

// myMath.js

// Default export
export default function add(x, y) {
  return x + y;
}

// Named export
export function subtract(x, y) {
  return x - y;
}

// Multiple exports
function multiply(x, y) {
  return x * y;
}
function duplicate(x) {
  return x * 2;
}
export { multiply, duplicate };
Copy after login

Asynchronous Processing

function helloWorld() {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve("Hello World!");
    }, 2000);
  });
}

async function msg() {
  const msg = await helloWorld();
  console.log("Message:", msg);
}

msg(); // Message: Hello World! <-- after 2 seconds
Copy after login

This quick reference guide covers a wide range of topics from the basics to more advanced JavaScript concepts. Be sure to download it here and make it a handy tool for your coding journey!

The above is the detailed content of JavaScript Cheat Sheets. For more information, please follow other related articles on the PHP Chinese website!

source:dev.to
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template
About us Disclaimer Sitemap
php.cn:Public welfare online PHP training,Help PHP learners grow quickly!