Learn JavaScript: Conditionals, Functions, and Scope

Continue with JavaScript foundations with conditionals, functions, and scope.

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Key Concepts

Review core concepts you need to learn to master this subject

Control Flow

Logical Operator ||

Ternary Operator

else Statement

Logical Operator &&

switch Statement

if Statement

Logical Operator !

Control Flow

Control flow is the order in which statements are executed in a program. The default control flow is for statements to be read and executed in order from left-to-right, top-to-bottom in a program file.

Control structures such as conditionals (if statements and the like) alter control flow by only executing blocks of code if certain conditions are met. These structures essentially allow a program to make decisions about which code is executed as the program runs.

Conditional Statements

Lesson 1 of 3

1
What are Conditional Statements?
In life, we make decisions based on circumstances. Think of an everyday decision as mundane as falling asleep — if we are tired, we go to bed, otherwise, we wake up and start our day. These …
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2
If Statement
We often perform a task based on a condition. For example, if the weather is nice today, then we will go outside. If the alarm clock rings, then we’ll shut it off. If we’re tired, then we’ll go to …
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3
If...Else Statements
In the previous exercise, we used an if statement that checked a condition to decide whether or not to run a block of code. In many cases, we’ll have code we want to run if our condition evaluates …
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4
Comparison Operators
When writing conditional statements, sometimes we need to use different types of operators to compare values. These operators are called comparison operators. Here is a list of some handy compar…
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5
Logical Operators
Working with conditionals means that we will be using booleans, true or false values. In JavaScript, there are operators that work with boolean values known as logical operators. We can use logic…
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6
Truthy and Falsy
Let’s consider how non-boolean data types, like strings or numbers, are evaluated when checked inside a condition. Sometimes, you’ll want to check if a variable exists and you won’t necessarily w…
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7
Truthy and Falsy Assignment
Truthy and falsy evaluations open a world of short-hand possibilities! Say you have a website and want to take a user’s username to make a personalized greeting. Sometimes, the user does not hav…
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8
Ternary Operator
In the spirit of using short-hand syntax, we can use a ternary operator to simplify an if…else statement. Take a look at the if…else statement example: let isNightTime = true; if (isNightT…
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9
Else If Statements
We can add more conditions to our if…else with an else if statement. The else if statement allows for more than two possible outcomes. You can add as many else if statements as you’d like, to mak…
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10
The switch keyword
else if statements are a great tool if we need to check multiple conditions. In programming, we often find ourselves needing to check multiple values and handling each of them differently. For exam…
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11
Review
Way to go! Here are some of the major concepts for conditionals: * An if statement checks a condition and will execute a task if that condition evaluates to true. * if…else statements make binar…
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