JS MASTER CLASS /// DECLARE FUNCTIONS /// MASTER ARROWS /// DRY CODE /// JS MASTER CLASS /// DECLARE FUNCTIONS /// MASTER ARROWS /// DRY CODE ///

JavaScript Functions

Master the building blocks of reusable logic: function declarations, anonymous expressions, and modern ES6 arrow syntax.

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Tutor:Functions are the heart of JavaScript. Think of them as reusable blocks of code. You write the logic once, and you can execute it as many times as you need without rewriting it.


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Declarations

Using the `function` keyword creates a named function. These are hoisted, so they can be called before they are defined.

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What keyword is used to create a function declaration?

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JavaScript Functions

Author

Pascual Vila

Senior Developer // Code Syllabus

A function in JavaScript is fundamentally a subprogram that can be called by code external (or internal) to the function. It's the core of reusable code. Let's break down the different syntax types.

Function Declarations

A function declaration defines a named function. One unique characteristic of declarations is Hoisting. JavaScript moves function declarations to the top of their scope before code execution, meaning you can call them before they appear in the file.

Function Expressions

A function expression can be anonymous (it has no name). You assign it to a variable, like const myFunc = function() {}. Unlike declarations, expressions are not hoisted. They only execute when the JavaScript engine reaches that line.

Arrow Functions

Introduced in ES6, Arrow Functions offer a more concise syntax (using =>). If the function is a single line, you can omit the curly braces and the `return` keyword for an implicit return. Furthermore, arrow functions do not bind their own `this` keyword, which is crucial for advanced object-oriented programming.

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This section contains the full detailed transcript covering the definition of functions, DRY principles (Don't Repeat Yourself), the execution context, difference between declarations and expressions, variable assignment of functions, and syntax rules for ES6 Arrow Functions.

JavaScript Glossary

Function Declaration

A traditional way to define a named function. It is hoisted to the top of its scope.

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Function Expression

A function created inside an expression, often anonymous and assigned to a variable.

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Arrow Function

ES6 syntax for a shorter function expression that does not bind its own 'this'.

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Invocation (Call)

Executing the code block inside a function by using its name followed by parentheses ().

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Anonymous Function

A function without a name. Often used in expressions or passed as callbacks.

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Implicit Return

In an arrow function, if you omit braces, the value is returned automatically without writing 'return'.

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