Why should you care?

Typeahead search for product names, filtering emails by domain, and finding SKUs by prefix all use regex — carefully, because leading-wildcard regex is slow.

See it live — copy this example

Open mongosh or MongoDB Compass, select database nosqlverse, then run the example. Change one field and run again.

db.products.insertMany([
  { name: "Sony WH-1000XM5", brand: "Sony" },
  { name: "sony portable speaker", brand: "Sony" },
  { name: "Boat Airdopes", brand: "Boat" }
])
db.products.find({ name: { $regex: /^sony/i } })
db.products.find({ name: /WH-1000/ })
db.products.find({ brand: { $regex: "oa", $options: "i" } })

Run Example »

Edit the code below and click Run to see the result in Toolliyo’s live editor.

What happened?

• First query finds names starting with sony ignoring case — both Sony products.
• Second finds the XM5 model substring.
• Third finds Boat via brand regex.
• Prefer prefix regex for index use when possible.

Practice next

1. Seed the products.
2. Run each regex find.
3. Try { name: { $regex: "sony", $options: "i" } } without ^.
4. Find emails ending with @gmail.com using $.
5. Search tags with regex on an array field.

Remember

$regex matches text patterns. Use i for case-insensitive. Prefer prefix searches for performance.

Admin SKU prefix lookup

Warehouse staff type “WH-” and the tool runs /^WH-/i on sku.

Outcome: Matching headsets appear without a full catalog scan when indexed.