JavaScript Coding without HTML and CSS Hangman

The 38 key terms

1console.log()

Prints a value or message to the browser or terminal console for debugging or output.

3let

Declares a variable whose value can be changed later.

4string

A data type that holds text, written inside quotes like "hello".

9typeof

An operator that returns a string naming the data type of a value.

10Number()

Converts a value, like a string, into a number data type.

13Falsy

A value that JavaScript treats as false in a boolean context, such as 0, "", null, undefined, or NaN.

15else if

Checks another condition only when the previous if or else if condition was false.

16else

Runs a block of code when every earlier if or else if condition was false.

18switch

Compares a value against multiple case labels and runs the code block for the matching case.

19while

Repeats a block of code as long as its condition inside parentheses stays true.

20for

Repeats a block of code a set number of times, using an initializer, condition, and update expression.

21break

Exits a loop completely, stopping it before it finishes all its passes.

23for...of

Loops directly over each value in an array, without needing an index.

24push()

Adds one or more elements to the end of an array, changing the original array.

25forEach()

Calls a given function once for every element in an array.

26map()

Creates a new array by running a given function on every element of the original array.

27filter()

Creates a new array containing only the elements that pass a test provided by a function.

28reduce()

Combines every element of an array into a single value using an accumulator function.

29length

The number of characters in a string, accessed as a property without parentheses.

30toUpperCase()

Returns a new string with all letters converted to uppercase.

31includes()

Checks whether a string contains a given substring, returning true or false.

33Object.keys()

Returns an array containing all the keys of a given object.

34for...in

Loops through each key (property name) of an object, one at a time.

35obj.pets[0]

Chains dot notation and bracket notation to access a value nested inside an object.

36destructuring

Unpacks values from an array or properties from an object into separate variables.

38function

Declares a reusable block of code with a name, which can be run later by calling it.

39parameter

A named placeholder inside a function's parentheses that receives an input value when called.

40return

Sends a value back out of a function and ends its execution at that point.

43scope

The area of code where a variable can be accessed; variables declared inside a function are local to it.

44try...catch

Runs code in a try block, and if an error occurs, runs the catch block instead of crashing.

45throw

Creates a custom error and immediately stops the current code from running further.

46JSON.stringify()

Converts a JavaScript value into a JSON-formatted string.

47class

Declares a blueprint for creating objects with shared properties and methods.

48constructor

A special method inside a class that runs automatically when a new instance is created.

49method

A function declared inside a class body, called on an instance using dot notation.

50extends

Lets a class inherit properties and methods from another class.

51new Map()

Creates a new Map, a built-in object that stores key-value pairs.

52new Set()

Creates a new Set, a built-in object that stores only unique values.