JavaScript Glossary

Array

An object in JavaScript which has multiple containers. This allows it to hold multiple values.

Assignment Operator

An operator which is used to set a variable to be equal to a string, number, Boolean operator, list, or date.

BOM

A browser object model (BOM) is a browser-specific convention which refers to all the objects exposed by a web browser.

Boolean Variable

A type of variable with two possible values, which are true or false. It is often used to determine a course of action within a program.

Break

A statement used to stop or get out of a loop.

Case

A text option which can be set to upper or lower. JavaScript is a case-sensitive language, so code and function names must be consistent to work correctly.

Ceiling

A method used in JavaScript to move numbers to a higher whole number.

Comment

A tool used to explain what code does and to tell JavaScript to ignore code temporarily.

Comparison Operator

An operator which is used inside JavaScript to compare arguments.

Console.log

A debugging tool in which requests can be entered to get information about selected script.

Constant

A variable which cannot change throughout its use in code.

Continue

A keyword which is used to skip a turn in a loop where a user is displaying a message or running an action a set number of times.

createElement

A method which is used to create dynamically an element and place that element in a specific spot on a webpage.

Data Localization

The process of using the toLocalDateString method to retrieve a date displayed in a localized format.

Debug

To try to find errors in code and then fix them.

Decrement

An assignment operator which decreases a value by one.

Do Loop

A loop that always runs at least once and then checks the condition.

Document.write

A method which allows the user to write both HTML elements and text to a webpage.

DOM

The Document Object Model (DOM) is an application programming interface which defines the structure and accessibility of a document.

Else If

A statement which checks a condition to see if it is true or false, and then takes action based on the result.

Else Statement

A statement used in conjunction with if and elif statements. It provides an if all else fails option.

Finally

A keyword which is used to deliver a final message to a user regardless of whether an argument was successful or not.

Floor

A JavaScript method used to move numbers to a lower whole number.

For Loop

A loop which will act for a set number of times before canceling.

Get

A method used to process data when trying to get information.

getElementByClassName

A method used in JavaScript to locate elements by their class name.

getElementById

A JavaScript method which is used to locate elements by ID.

getElementsByTagName

A method which is used to locate elements by its tag name.

If

A statement used in JavaScript which checks a condition to see if it is true or false, and then takes action based on the result.

Increment

An assignment operator which increases a value by one.

Indentation

The process of moving code to the right in order to make it easier to read, but also to complete if statements.

Index Number

A tool which is used to access an element inside of an array.

Initialization

The act of storing a value in a variable in JavaScript.

innerHTML

A property in JavaScript which allows the user to control dynamically the text in between the opening and closing tag of an existing HTML element.

Instantiation

A tool used to create a new template for an object, otherwise known as a class.

Logical Operator

A symbol used in a logical statement to determine the logic between values. Examples would include &&, !, ||, and others.

Loop

A statement which allows code to be executed multiple times.

Masking Value

A tool used in JavaScript to mask or hide characters typed into sensitive fields on a form, such as a password field. Setting an input field to a password type field will mask the field.

Math.abs

A method used in JavaScript to make a number represent absolute value.

Max

A method used in JavaScript to retrieve the highest numbers from a range of numbers.

Method

A tool within JavaScript which is used to take action on objects and their properties.

Min

A JavaScript method which retrieves the lowest numbers from a range of numbers.

Modulus

The term used to indicate the remainder when dividing whole numbers in JavaScript.

NaN

Not a Number (NaN) is an indicator which will usually appear when a calculation expecting a number takes place.

Nested If

An if statement that is placed inside of another if statement.

Noscript

A tag which is used to ensure that JavaScript code works on a browser that does not support JavaScript.

Null

An empty variable on a webpage which has been declared and is defined as empty but not zero.

Number

A variable in JavaScript which is used to store data as floating point decimals.

Object

An item in JavaScript which can be manipulated.

Onclick

One of the most commonly used events in JavaScript, it triggers code when an object is clicked.

Onchange

An event which executes when an object is changed.

Onkeydown

An event which will trigger when a user presses a key on a keyboard.

Onload

An event in JavaScript which occurs when an HTML element loads.

Onmouseout

Similar to an onmouseover event, this event triggers when a mouse is moved away from an object.

Onmouseover

A JavaScript event which triggers when a user rolls a mouse over an object.

Onsubmit

The event used to run, or validate, any last code before a form sends its data to be processed.

Pop

Similar to push, it is a tool used to remove the last item from an array.

Post

A method used to process data when a user is posting information somewhere.

Pow

A type of method in JavaScript which takes a number and raises it to a specified power.

Prepopulating Value

A value option which is set in a form field prior to a user filling it out.

Property

A characteristic of an object within JavaScript.

Push

An array concept which is used to add an item to an array.

RNG

A random number generator (RNG) is used to add the randomly generated numbers to a game, creating the element of surprise.

Round

A method used in JavaScript to round a number to the nearest whole number.

Scope

An item within JavaScript which defines the depth to where a variable can be used in a file. Two factors determine scope: where the variable is declared and whether it is explicitly declared, meaning whether the var keyword is being used.

Shift

A method which is used to remove the first item from an array.

Single-Dimensional Array

An array with a single object that only has one group of values.

Sqrt

A type of method which calculates the square root of a number.

String

One of the most common variables in JavaScript, it is used to store text, numbers, symbols, and other characters.

Switch

A conditional statement which compares code against multiple cases and executes one or more blocks of code based on matching cases.

Try/Catch

A block in which code tries to run and, if there is an error, the catch part controls what happens next.

typeOf Operator

A tool used in JavaScript which reveals the data type that is assigned to a variable.

Undefined

An empty variable which had been declared but has no value.

Unshift

An array method which is used to add an item to the beginning of an array.

Use Strict

A command used to force every variable in a function to be explicitly declared as a variable.

Validation

The act of making sure valid data is entered on a form before the form is submitted. The two most common validation tasks are to make sure required fields are filled out and to make sure the correct type of data is entered into a field.

Variable

A container which is used to hold information in JavaScript that can be used later in the code.

While Loop

A loop which proposes an argument where if something is true or false it will run a designated code.

Window

An object which represents a browser window in JavaScript.