1. JavaScript Foundations
JavaScript is a high-level, interpreted programming language that runs in every modern browser and is the scripting language of the Web. It was created by Brendan Eich in 1995 whil...
Read full chapter →The essential Javascript Fundamentals cheat sheet: 8 concise chapters you can read in minutes, distilled from the full deck. When you're ready, drill the flashcards or test yourself under exam conditions.
JavaScript is a high-level, interpreted programming language that runs in every modern browser and is the scripting language of the Web. It was created by Brendan Eich in 1995 whil...
Read full chapter →JavaScript offers three keywords for declaring variables: var, which is function-scoped, and let and const, both of which are block-scoped and were introduced in ES6. const declare...
Read full chapter →Programs make decisions with if, else if, and else blocks. The condition in an if statement is evaluated for truthiness, and JavaScript will coerce any non-boolean value into a boo...
Read full chapter →JavaScript's two main collection types are arrays and objects. Arrays are created with square brackets, for example const arr = [1, 'a', true]; or with the new Array() constructor,...
Read full chapter →Scope is the region of code where a variable is accessible. The outermost region is the global scope, available everywhere in a script. Variables declared with var are function-sco...
Read full chapter →Even though ES6 introduced the class keyword, JavaScript's object system is built on prototypes. The prototype chain is how JavaScript looks up a property: if it is not found on an...
Read full chapter →Long-running operations like network requests must run asynchronously so the browser stays responsive. JavaScript represents these operations with Promises, which are objects that...
Read full chapter →JavaScript's classic role is to manipulate the Document Object Model (DOM). You can select a single element with document.getElementById('id') or document.querySelector('.class'),...
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