JavaScript glossary: Apprentice level
74 JavaScript terms at the Apprentice level, each with a short definition and a link to its full page.
Updated
- Argument
- The actual value you hand to a function when you call it.
- Arguments (JavaScript)
- An argument is any value that is passed into a function when calling the function.
- Array
- A fixed-size, indexed collection whose elements all have the same type.
- Array - Mixed Types - JavaScript
- TRUE - JavaScript arrays can contain multiple types in the same array.
- Array Destructuring
- Syntax that extracts array items by position into variables.
- Array Index
- A zero-based number that identifies an element's position in an array.
- Array Length
- The fixed number of elements an array can hold.
- Arrow Function
- A compact function expression written with the => symbol.
- Bracket Notation
- Accessing an object property with a key expression inside square brackets.
- break
- Stops a loop immediately.
- Callback Function
- A function passed to other code to be called later or during an operation.
- continue
- Skips to the next pass of the loop.
- Date Object
- A built-in object representing a single moment in time.
- Default Parameter
- A parameter value used when the caller supplies undefined or omits the argument.
- describe, it and expect
- Group tests, define tests, and assert results.
- do...while Loop
- A loop that runs its body once before checking whether to repeat.
- Dot Notation
- Accessing an object property with a dot followed by its name.
- Escape Sequence
- A backslash code that represents a special character inside a string or character literal.
- Event - JavaScript
- An event is an any action that can happen that your application can monitor.
- for Loop
- Repeats code once for each item in a collection.
- for...in Loop
- A loop that visits an object's enumerable property names.
- for...of Loop
- A loop that visits the values produced by an iterable.
- Function
- A reusable block of code that can receive values and return a result.
- Function Declaration
- A named function created with the function keyword as a statement.
- Function Expression
- A function created as part of an expression and commonly assigned to a variable.
- Function Signature (JavaScript)
- Functions have a signature, this is how the JavaScript runtime knows what code block to…
- Global Scope
- The outermost scope, whose declarations may be available across a script or module.
- How to call a function
- A function is called by specifying the name of the function followed by parentheses and…
- includes()
- A method that reports whether an array contains a value or a string contains text.
- Jest
- A popular JavaScript test framework.
- join()
- Glues a list of strings into one string with a separator between them.
- JSON Object
- A built-in object with methods for converting between JavaScript values and JSON text.
- Key-Value Pair
- One entry in a dictionary: a key and the value stored under it.
- Local Scope
- A function or block scope where declarations are available only inside that area.
- Looping Logic
- Math Object
- A built-in object containing mathematical constants and functions.
- Math.random()
- A method that returns a pseudorandom double from 0.0 up to, but not including, 1.0.
- Method
- A function that belongs to a class, called on an object with a dot.
- Nested Array
- An array containing one or more arrays as its items.
- Nested Loop
- A loop inside another loop.
- Nullish Coalescing
- The ?? operator, which uses a fallback only when its left value is null or undefined.
- Object
- A class instance that combines its own state with available behavior.
- Object - JavaScript
- A JavaScript object gives you the ability to store multiple related variables in the same…
- Object Destructuring
- Syntax that extracts named object properties into variables.
- Object Literal
- Brace syntax that creates an object from a list of properties.
- Optional Chaining
- The ?. operator, which stops and returns undefined when the value before it is nullish.
- Parameter
- A name in a function definition for a value the function needs.
- Parameter (JavaScript)
- A parameter (also known as an input parameter) is a way of receiving a variable into a…
- Parameters and Arguments (JavaScript)
- A parameter is defined by the function to specify what input is required to call the…
- parseFloat()
- A function that reads a decimal number from the beginning of a string.
- parseInt()
- A function that reads a whole number from the beginning of a string.
- pop()
- Removes an item from a list and hands it back (the last one by default).
- Property
- A member that exposes a value through get and set accessors.
- push()
- An Array method that adds values to the end and returns the new length.
- Rest Parameter
- A final function parameter beginning with ... that collects remaining arguments into an array.
- Return Value
- The result a function hands back with return.
- Return Value (JavaScript)
- Functions may or may not return a response value when they are called.
- Scope
- Where in the code a variable can be used.
- shift()
- An Array method that removes and returns the first item.
- slice()
- A method that returns a selected portion without changing the original array or string.
- splice()
- An Array method that removes, replaces, or inserts items by changing the original array.
- split()
- Breaks a string into a list of pieces.
- Spread Syntax
- The ... syntax that expands values from an iterable or properties from an object.
- String Concatenation
- Joining strings end to end with +.
- String Index
- A zero-based position used to locate a character in a String.
- String Length
- The number of UTF-16 code units in a String.
- String Parsing
- Strings cannot be directly converted to another data type, but strings can represent…
- Ternary Operator
- The ?: operator, which chooses one of two values from a condition.
- The DOM
- A browsers in-memory representation of the HTML document.
- this
- A value supplied by the way a regular function is called, often referring to the receiving object.
- toString()
- A method that returns a readable text representation of an object.
- unshift()
- An Array method that adds values to the beginning and returns the new length.
- Vitest
- A fast JavaScript test runner built on Vite.
- while Loop
- Keeps repeating as long as its condition stays true.