JavaScript Interview Secrets Unleashed! 🚀

Web Wizards Assemble!

Prerequisites

• Web Wisdom: Basic knowledge of the web and programming.

• Code Sorcery: Mastered HTML/CSS and wield the magic of JavaScript, especially ES6+ spells.

Table Of Contents 📚

1. JavaScript Basics 👶

   • Variables: Three magical ways to summon them: var, let, and const.

    let wizardPower = 42; // Const spells an unchanging power

• Equality Enchantment: == vs ===. Beware! One cares about types.

    let a = 5;
    let b = '5';
    console.log(a == b); // true, but a === b is false!

• Arrays Arsenal: Storing magical items in arrays.

    const spells = ['levitate', 'fireball', 'invisibility'];

1. Functional Enchantment 🛠️

   • Scope Sorcery: Where wizards can see and cast spells.

    function magicCircle() {
       let wand = 'Phoenix Feather';
       console.log(wand); // Phoenix Feather
    }

• Closures Conundrum: Hidden magical realms.

    function enchantment() {
       let power = 'Cosmic';
       return () => console.log(`Power of ${power} unleashed!`);
    }

• Prototypal Inheritance Parade: Objects and their magical offspring.

    const dragon = {
       breatheFire() {
          console.log('Spewing fire!');
       },
    };
    const redDragon = Object.create(dragon);

1. Asynchronous Chronicles ⚡

   • Event Loop Expedition: The mystical journey of JavaScript.

    setTimeout(() => {
       console.log('Time travel complete!');
    }, 2000);

• Promises Prowess: Vows made and kept in the magical realm.

    const spellBook = new Promise((resolve, reject) => {
       if (isWizard) {
          resolve('Magic Unleashed!');
       } else {
          reject('Spell Backfired!');
       }
    });

1. Advanced Magic Concepts 🧙‍♂️

   • Polyfills Potency: Filling in gaps for ancient browsers.

    Array.prototype.myMap = function (callback) {
       // Implementation of map for ancient browsers
    };

• Async and Defer Dazzle: Script loading strategies.

    <script src="magic.js" async></script>
    <script src="more_magic.js" defer></script>

• Debouncing Delight: The art of patience in spellcasting.

    const spellSearch = debounce(searchSpell, 300);
    searchInput.addEventListener('keyup', spellSearch);

1. Storage Sorcery 💾

   • localStorage Lumos: Preserving magical artifacts.

    localStorage.setItem('wand', 'Elder Wand');
    let myWand = localStorage.getItem('wand');

🎩 Wizard’s Caveat

• This cheatsheet focuses on interview-worthy spells, not an exhaustive magical grimoire.