window.prompt() Prompt dialog
Last updated: 2026-09-09
window.prompt() Prompt dialog
prompt shows a dialog with an input field, returning the entered string or null.
| Category | Browser (BOM) |
|---|---|
| ES version | DOM |
📝 Syntax
const input = prompt(message, defaultValue);⚙️ Parameters
| message | The prompt message. |
|---|---|
| defaultValue | Optional. Default input value. |
Returns：The entered string, or null if cancelled.
Mutates the original：No (returns a new value)
▶ Example
Edit the code, press Run, and see the result in the output panel:
Output：
Hello, Guest💡 Tip prompt returns null for cancel — distinguish from empty string.
⚠️ Warning prompt blocks the page — use custom inputs in production.
🌐 Browser support
| Browser |  Chrome |
 Edge |
 Firefox |
 Safari |
 Opera |
|---|---|---|---|---|---|
| window.prompt() | ✓ v1 | ✓ v12 | ✓ v1 | ✓ v1 | ✓ v1 |
| Supported by all modern browsers | |||||
🏷️ Related Items
💡 Related Cases
More case studies coming soon — check back later.
📚 Related Tutorials
❓ FAQ
Qprompt null vs empty string?
Anull = cancelled; empty string = OK with no input.
QCan prompt restrict input type?
ANo — always a string; validate manually.
QThe default value parameter?
AThe second argument prefills the input.
