VARIABLES
Review Variables
Nice work! This lesson introduced you to variables, a powerful concept you will use in all your future programming endeavors.
Let’s review what we learned:
- Variables hold reusable data in a program and associate it with a name.
- Variables are stored in memory.
- The var keyword is used in pre-ES6 versions of JS.
- let is the preferred way to declare a variable when it can be reassigned, and const is the preferred way to declare a variable with a constant value.
- Variables that have not been initialized store the primitive data type undefined.
- Mathematical assignment operators make it easy to calculate a new value and assign it to the same variable.
- The + operator is used to concatenate strings including string values held in variables
- In ES6, template literals use backticks ` and ${} to interpolate values into a string.
- The typeof keyword returns the data type (as a string) of a value.
Instructions
To learn more about variables take on these challenges!
- Create variables and manipulate the values
- Check what happens when you try concatenating strings using variables of different data types
- Interpolate multiple variables into a string
- See what happens when you use console.log() on variables declared by different keywords (const, let, var) before they’re defined. For example:
JavaScript:
console.log(test1);
const test1 = 'figuring out quirks';
- Find the data type of a variable’s value using the typeof keyword on a variable.
- Use typeof to find the data type of the resulting value when you concatenate variables containing two different data types.