True Basics Flashcards
How do you do one line comments in javascript ?
// enter comment here // enter comment2 here
How do you do multi-line comments in javascript?
/* comment blah blah blah */ this line ends the comment
How do you assign a value to a string variable?
var name = “george” ;
What does initializing a variable mean
assigning an initial value to a variable.
What date type does a variable value have if you do not assign a value?
undefined
Are variables case sensitive in javascript?
yes
Write three words together as one word to show you understand what camel case is.
helloMyFriend
What data type is the value 5 in javascript?
number
_____is a data type in javascript which represents numeric data
number
How do you add two numeric values in Javascript
5 + 5
How do you subtract two numeric values in javascript
7 - 3
How do you multiply two numeric values in javascript
7 * 3
How do you divide two numeric values in javascript
9 / 3
How do you increment the number of a variable in javascript (suppose i is the variable)
i++
How do you decrement the number of a variable in javascript (suppose i is the variable)
i–
What data type stores decimal numbers?
floating point
What is the operator for remainder
%
What what does the remainder operator return
The remainder that’s left over after division
Rewrite myVar = myVar + 5 into a compound assignment
myVar += 5
Rewrite myVar = myVar - 5 into a compound assignment
myVar -= 5
Rewrite myVar = myVar * 5 into a compound assignment
myVar *= 5
What does escaping a quote mean?
When you use the backslash from within quotations to include the same quotation character as a part of it.
How do you escape the “ character
"
How do you escape the ‘ character
'
how do you escape a backslash
\
how do you escape a new line?
\n
how do you escape a carriage return?
\r
how do you escape a tab?
\t
how do you escape a word boundary?
\b
how do you escape a form feed?
\f
How do you concatenate two string fields together?
“string content 1” + “string content 2”
How do you concatenate two strings together (through a variable) using the same sequence that represents incrementing a number?
var ourStr = "I come first. "; ourStr += "I come second.";
How do you find the length of the value of a variable
Assume variable is called variableName
variableName.length
How do you find the first character of a string variable
Assume variable is called variableName
variableName[0]
How do you find the second character of a string variable
Assume variable is called variableName
variableName[1]
How do you find the third character of a string variable
Assume variable is called variableName
variableName[2]
How do you find the last character in a string variable?
Assume variable is called variableName
variableName[variableName.length -1]
How do you find the second last character in a string variable?
Assume variable is called variableName
variableName[variableName.length -2]
_______ are the classifications we give to the different kinds of data that we use in programming.
data types
In JavaScript, there are _____ fundamental data types:
seven
What is the data type for Any number, including numbers with decimals: 4, 8, 1516, 23.42
number
What is the data type for any grouping of characters on your keyboard (letters, numbers, spaces, symbols, etc.) surrounded by single quotes: ‘ … ‘ or double quotes “ … “. Though we prefer single quotes.
string
This data type only has two possible values— either true or false (without quotes).
boolean
This data type represents the intentional absence of a value, and is represented by the keyword ____ (without quotes).
null
This data type is denoted by the keyword ____(without quotes). It also represents the absence of a value though it has a different use than null.
undefined
A newer feature to the language, ______ are unique identifiers, useful in more complex coding. No need to worry about these for now.
symbols
What are objects?
Object: Collections of related data.
Operators aren’t just for numbers! When a + operator is used on two strings, it _____ the right string to the left string
appends
This process of appending one string to another is called
concatenation
Every string has a property called _____ that stores the number of characters in that string.
length
What are methods?
Actions we can perform in javascript.
To use a method on a string how do we call the method?
by appending an instance with a period (the dot operator), the name of the method, and opening and closing parentheses: e.g. ‘example string’.methodName().
When we use console.log() we’re calling the ___method on the ____ object
log method
console object
When we use console.log() we’re calling the log method on the ____ object
console
When we use console.log() we’re calling the ____method on the console object
log
write a console.log statement that would convert what would be the output “dead tree” to upper case.
console.log(‘dead tree’.toUpperCase());
write a console.log statement that would remove the whitespace in string ‘ Remove whitespace ‘
console.log(‘ Remove whitespace ‘.trim());
Write a console.log statement that would return a random floating point number between 0 and 100.
console.log(Math.random() * 100);
What method takes a decimal number, and rounds down to the nearest whole number.
Math.floor()
How would you ensure a whole number output that generates a random number between 0 and 100 using a console.log statement
console.log(Math.floor(Math.random() * 100));
Find a method on the JavaScript Math object that returns the smallest integer greater than or equal to a decimal number.
Use this method with the number 43.8. Log the answer to the console.
console.log(Math.ceil(43.8)) ;
The ______ method is used to log or print messages to the console. It can also be used to print objects and other info.
console.log()
______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.
Javascript
JavaScript is a programming language that powers the dynamic behavior on most websites. Alongside ____ and CSS, it is a core technology that makes the web run.
html
JavaScript is a programming language that powers the dynamic behavior on most websites. Alongside HTML and ___, it is a core technology that makes the web run.
css
_____return information about an object, and are called by appending an instance with a period ., the ____ name, and parentheses.
methods
_______ contain methods that can be called by appending the library name with a period ., the method name, and a set of parentheses.
libraries
Numbers
_____ are a primitive data type. They include the set of all integers and floating point ______.
number
The _____ property of a string returns the number of characters that make up the string.
.length
When a new piece of data is introduced into a JavaScript program, the program keeps track of it in _______ of that data type.
an instance
An instance is an individual case of a _____
data type
An ____ is an individual case of a data type.
instance
______ are a primitive data type. They can be either true or false.
booleans
The ______ function returns a floating-point, random number in the range from 0 (inclusive) up to but not including 1.
Math.random()
The _____ function returns the largest integer less than or equal to the given number.
Math.floor()
In JavaScript, single-line comments are created with
two consecutive forward slashes //.
____ is a primitive data type. It represents the intentional absence of value. In code, it is represented as ____
null
______ are a primitive data type. They are any grouping of characters (letters, spaces, numbers, or symbols) surrounded by single quotes ‘ or double quotes “
strings
Arithmetic Operators - what is the operator for addition
+
Arithmetic Operators - what is the operator for subtraction
-
Arithmetic Operators - what is the operator for multiplication
*
Arithmetic Operators - what is the operator for division
/
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.
/* at beginning */ at end
An assignment operator assigns a value to its left operand based on the value of its right operand.
Write number = number + 10 in a way that demonstrates the additional assignment
number += 10
An assignment operator assigns a value to its left operand based on the value of its right operand.
Write number = number - 7 in a way that demonstrates the subtraction assignment
number -= 7
An assignment operator assigns a value to its left operand based on the value of its right operand.
Write number = number * 3 in a way that demonstrates the multiplication assignment
number *= 3
An assignment operator assigns a value to its left operand based on the value of its right operand.
Write number = number / 10 in a way that demonstrates the division assignment
number /= 10
_____ 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
What is the way to declare a variable in pre-ES6 versions of javascript
var = value
What is the preferred way to declare a variable in javascript post-ES6 if the value can be reassigned later
let = value
What is the preferred way to declare a variable in javascript post-ES6 if the value should remain constant
const = value
Template literals are strings that allow embedded expressions, ${expression}. While regular strings use single ‘ or double “ quotes, template literals use backticks instead.
Embed the variable name into a console.log expression saying hello to the users
console.log (Hello, ${name})
____ hold reusable data in a program and associate it with a name.
variables
Variables are stored in ___
memory
The var keyword is used in ____ versions of JS.
pre-ES6
____is the preferred way to declare a variable when it can be reassigned
let
____is the preferred way to declare a variable with a constant value
const
Variables that have not been initialized store the primitive data type _____
undefined
The __operator is used to concatenate strings including string values held in variables
+
The + operator is used to _____ strings including string values held in variables
concatenate
In ES6, template literals use backticks ` and ____to interpolate values into a string.
${}
In ES6, ______ use backticks ` and ____to interpolate values into a string.
template literals
