100+ JS Functions and Syntax: A Comprehensive Guide for Front-End Developers

As a front-end developer, having a solid foundation of JavaScript syntax and functions is essential. In this article, we'll cover over 100 commonly-used JavaScript functions and syntax, with detailed explanations and practical examples.

Basic Syntax

Variables

Variables are used to store data in JavaScript. There are three keywords to declare a variable: var, let, and const.

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Data Types

JavaScript has six primitive data types: string, number, boolean, null, undefined, and symbol. Objects are another type in JavaScript.

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Operators

Operators are used to perform actions on variables and values. Some common operators in JavaScript include:

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Control Flow

Control flow statements are used to control the order in which statements are executed. Common control flow statements include if-else, for, while, and switch.

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Functions

Functions are blocks of code that can be called to perform a specific task. They can also accept parameters and return values.

Function Declaration

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Function Parameters

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Function Return Values

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Arrow Functions

Arrow functions are a concise way to write functions in JavaScript.

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Higher-Order Functions

Higher-order functions are functions that accept other functions as arguments or return functions as values.

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Arrays

Arrays are used to store collections of data in JavaScript. They can be of any data type and can be accessed by index.

Array Declaration

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Accessing Array Elements

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