JavaScript glossary: Novice level
50 JavaScript terms at the Novice level, each with a short definition and a link to its full page.
Updated
- <script> Element
- An HTML element that loads or contains JavaScript for a web page.
- Arithmetic Operators
- The math symbols: + - * / // % **.
- Arithmetic Operators (JavaScript)
- 3 + 4 // addition
- Array - Access Element - JavaScript
- Array indexes are 0 based.
- Array - JavaScript
- An array is a collection of multiple values in a single variable.
- Assignment
- Storing a value in a variable with a single =.
- BigInt
- A numeric primitive for integers larger than Number can safely represent.
- Block Scope
- The region inside braces where let and const declarations are available.
- Browser Console
- A browser development panel for inspecting messages, errors, and JavaScript values.
- camelCase
- A naming style that starts lowercase and capitalizes each later word.
- Character - JavaScript
- A character is a single letter, digit, punctuation or any other special character.
- Comment
- Text written for people reading the code that the JavaScript engine ignores.
- Comparison Operators
- Symbols like == and < that compare two values and answer True or False.
- console.log()
- A method that writes a value to the runtime's development console.
- const
- A keyword that declares a block-scoped variable that can't be given a new value.
- ECMAScript
- The language standard that defines how JavaScript syntax and behavior work.
- else Statement
- A branch that runs when its matching if condition is falsy.
- Falsy
- A value treated as false when JavaScript evaluates it as a condition.
- if Statement
- Runs a block of code only when a condition is true.
- JavaScript
- A programming language used to add behavior to web pages and build applications in browsers, servers, and other runtimes.
- JavaScript Data Types
- JavaScript basic data types are string, number and boolean.
- JavaScript Engine
- Software that reads and executes JavaScript code.
- JavaScript Runtime
- An environment combining a JavaScript engine with APIs such as timers, files, or browser features.
- JavaScript variable
- A variable is a named alias for a value that you want to use in your application.
- let
- A keyword that declares a block-scoped variable that can be reassigned.
- Logical Operators
- and, or and not: they combine True/False checks.
- Naming Conventions (JavaScript)
- JavaScript predominantly uses 2 naming conventions: camelCase and PascalCase.
- NaN
- A special Number value meaning the result is not a valid number.
- Node.js
- A JavaScript runtime commonly used for servers, command-line tools, and automation.
- null
- A primitive value deliberately used to represent no object or value.
- Number
- JavaScript's main numeric type for both whole and fractional numbers.
- Primitive Value
- A value that is not an object, such as a string, number, boolean, null, or undefined.
- Runtime Error
- A problem that occurs while a compiled program is running.
- Script
- A file or block of JavaScript code that a browser or another runtime can execute.
- Semicolon
- A punctuation mark that can end a JavaScript statement.
- Snake Case
- All letters are lower case, each word is separated by an underscore.
- Strict Equality (===)
- A comparison that requires equal values and matching types without coercion.
- String
- Text inside quotes, like \"hello\" or 'coffee'.
- String - JavaScript
- A string is a series of characters (letters and/or digits).
- String Interpolation
- Placing an expression inside ${} so its value becomes part of a template literal.
- switch Statement
- A statement that selects a code path by matching one value against cases.
- Syntax Error
- An error caused by code that does not follow JavaScript's grammar.
- Template Literal
- A string enclosed by backticks that supports interpolation and multiple lines.
- Truthy
- A value treated as true when JavaScript evaluates it as a condition.
- Type Coercion
- JavaScript's conversion of a value from one type to another, either automatically or explicitly.
- typeof Operator
- An operator that returns a string describing a value's basic type.
- undefined
- The primitive value used when a value has not been assigned or is missing.
- var
- An older keyword for declaring a variable that belongs to the whole function, not just the block it's in.
- Variable
- A name that holds a value, like a labelled box.
- Variable Declaration
- A statement that creates a variable name with let, const, or var.