JavaScript Variables

Use const and let for values.

JavaScript

const name = "Ada";
let score = 82;
score += 9;
console.log(name, score);

Output

Ada 91

Explanation

Use const when you will not reassign a binding. Use let when reassignment is needed. Prefer clear names and avoid var in new code.

Explore the dry run

Guided walkthroughReady

1const name = "Ada";

2let score = 82;

3score += 9;

4console.log(name, score);

Start to inspect the source, values, and output. These prepared steps explain the published sample; grouped loop steps describe multiple iterations.

View the complete dry-run table

Prepared trace of the published program. Some rows group repeated iterations.
What happens	State after step	Output so far
Bind name to Ada.	`name = "Ada"`	—
Initialize score to 82.	`score = 82`	—
Add 9 and assign the result back to score.	`score = 91`	—
Log both values.	`score = 91`	Ada 91