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JavaScript
Strings, numbers, arrays, maps, sets, dates, regex, and the built-ins you use every day.
Strings are for storing text
JavaScript has only one type of number.
JavaScript Date Objects let us work with dates:
An Array is an object type designed for storing data collections.
A JavaScript Set is a collection of unique values.
A JavaScript Map is an object that can store collections of key-value pairs, similar to a dictionary in other programming languages.
The JavaScript Math object allows you to perform mathematical tasks.
A Regular Expression is a sequence of characters that forms a search pattern .
Beloved child has many names
The toString() method returns a number as a string.
There are generally 3 types of JavaScript date input formats:
Complete JavaScript Array Reference
Pass an array to the new Set() constructor:
You can create a map by passing an array to the new Map() constructor:
Math.random() returns a random number between 0 (inclusive), and 1 (exclusive):
Flags are parameters that can modify how a regex pattern is used, such as making it case-insensitive or global.
Javascript strings are primitive and immutable: All string methods produce a new string without altering the original string.
Number.EPSILON is the difference between the smallest floating point number greater than 1 and 1.
In JavaScript, date objects are created with new Date() .
Complete JavaScript Array Reference
Set Logic is an ECMAScript 2025 feature.
A JavaScript WeakMap is a collection of key/value pairs where the keys must be objects .
Character Classes are characters enclosed in square brackets [] .
The indexOf() method returns the index (position) of the first occurrence of a string in a string, or it returns -1 if the string is not found:
JavaScript stores numbers as 64 bits floating point numbers, but all bitwise operations are performed on 32 bits binary numbers.
Set Date methods let you set date values (years, months, days, hours, minutes, seconds, milliseconds) for a Date Object.
Complete JavaScript Array Reference
A JavaScript WeakSet is a collection of values where the values must be objects .
Metacharacters are characters with a special meaning.
BigInt is a JavaScript data type for handling and storing big integer values .
Array iteration methods operate on every array item.
Assertions matches Boundaries and Lookarounds :
In 2015, JavaScript introduced an important new keyword: const .
Quantifiers define the numbers of characters or expressions to match.
Flags can be added to a regexp pattern to Modify its behavior:
In JavaScript, RegExp is a regular expression object with predefined properties and methods.
JavaScript RegExp Flags