Term pt.1(intro) Flashcards
Console.log()
Method used to log or print messages to the console. It can also be used to print objects and other info.
JavaScript
JavaScript is a programming language that powers the dynamic behavior on most websites. Alongside HTML and CSS, it is a core technology that makes the web run.
Methods
Methods return information about an object, and are called by appending an instance with a period ( . ), the method name, and parentheses.
Libraries
Libraries contain methods that can be called by appending the library name with a period ( . ), the method name and a set of parentheses.
Numbers
Numbers are primitive data type. They include the set of all integers and floating point numbers.
String.length
The (.length) property of a string returns the number of characters that make up the string.
Data Instances
When a new piece of data is introduced into a JavaScript program, the program keeps track of it in an instance of that data type. An instance is an individual case of a data type.
Booleans
Booleans are a primitive data type. They can be either “True” or “False”
Math.random()
The Math.random() function returns a floating-point, random number in the range from 0 (inclusive) up to but not including 1.
Math.floor()
The Math.floor() function returns the largest integer less than or equal to the given number.
Single Line Comments
In JavaScript, single-line comments are created with two consecutive forward slashes ( // ).
Null
Null is a primitive data type. It represents the intentional absence of value. In code, it is represented as null.
Strings
Strings are a primitive data type. They are any grouping of characters (letters, spaces, numbers, or symbols) surrounded by single quotes ( ‘ ) or double quotes ( “ ).
Aritmethic Operators
JavaScript supports arithmetic operators for: ( +, - addition - , - subtraction * , - multiplication / , - division % - modulo)
Multi-line Comments
In JavaScript, multi-line comments are created by surrounding the lines with ( /* ) at the beginning and ( */ ) at the end. Comments are good ways for a variety of reasons like explaining a code block or indicating some hints, etc.
Remainder/Modulo Operator(%)
The remainder operator, sometimes called modulo, returns the number that remains after the right-hand number divides into the left-hand numbers as many times as it evenly can.
Assignment Operators
An assignment operator assigns a value to its left operand based on the value of its right operand. Here are some of them. \+= addition assignment -= subtraction assignment *= multiplication assignment /= division assignment
String Interpolation
String interpolation is the process of evaluating string literals containing one or more placeholders ( expressions, variables, etc ).
Variables
Variables are used whenever there’s a need to store a piece of data. A variable contains data that can be used in the program elsewhere. Using variables also ensures code re-usability since it can be used to replace the same value in multiple places.
Undefined
( undefined ) is a primitive JavaScript value that represents lack of defined value. Variables that are declared but not initialized to a value will have the value ( undefined ).
let Keyword
( let ) creates a local variable in JavaScript & can be re-assigned. Initialization during the declaration of a ( let ) variable is optional. A ( let ) variable will contain ( undefined ) if nothing is assigned to it.
const Keyword
A constant variable can be declared using the keyword ( const ). It must have an assignment. Any attempt of re-assigning a ( const ) variable will result in JavaScript runtime error.
String Concatenation
In JavaScript, multiple strings can be concatenated together using the ( + ) operator. In the example, multiple strings and variables containing string values have been concatenated. After execution of the code block, the ( displayText ) variable will contain the concatenated string.
Floating Point
Primitive data stored as decimal numbers. Decimal numbers are sometimes referred to as a floating point numbers or floats.
