Variables and strings — JavaScript Fundamentals lesson

Repeating the same value over and over gets tedious — and error-prone. Variables let you name a value once and reuse it. In this lesson you'll store a name and an age in variables, then build a sentence that includes both.

What you'll learn

Declare variables with const and let
Combine strings with + or template literals
Pick const vs let based on whether the value should change

Instructions

Create two variables:

name, a string, set to "Ada"
age, a number, set to 36

Then print exactly:

Hi, I'm Ada and I'm 36 years old.

Use at least one const in your solution (any of the variables is fine — they don't change).

Key concepts

Declaring variables

const name = "Ada";
let age = 36;

const declares a value that won't be reassigned. Use it by default.
let declares a value that will change (counters, accumulators, etc.).

Reassigning a const throws an error; reassigning a let is fine:

let count = 0;
count = count + 1;  // OK

const pi = 3.14;
pi = 3;             // TypeError: Assignment to constant variable.

Joining strings

Two ways to build a sentence out of variables:

Concatenation with +:

console.log("Hi, I'm " + name + " and I'm " + age + " years old.");

Template literals (backticks):

console.log(`Hi, I'm ${name} and I'm ${age} years old.`);

Template literals are usually easier to read — especially when you have multiple variables or want to write text that includes quote characters. The ${...} syntax drops a variable (or any expression) straight into the string.

Hints

You need two variables and one console.log.
Use const name = "Ada"; and pick const or let for age.
console.log(\Hi, I'm ${name} and I'm ${age} years old.\);