JS RegExp Classes
Character classes describe which characters may occur at one position. A range such as A-Z matches one uppercase ASCII letter.
Where to run this
This example uses the JavaScript console playground. Select Run to execute it; the example does not run on this lesson page.
A practical example
console.log("AB-42".match(/[A-Z]/g));
console.log("AB-42".match(/\d/g));
What happens
The separate matches are A and B, then 4 and 2.