# Lookahead for password rules

`/^(?=.*[a-z])(?=.*[A-Z])(?=.*\d).{8,}$/`

**Match a whole string consisting of a position followed by zero or more of any character, then "a" to "z", then a position followed by zero or more of any character, then "A" to "Z", then a position followed by zero or more of any character, then a digit, then 8 or more of any character.**

## Step by step

- `^` — Anchor to the start of the input.
- `(?=.*[a-z])` — Match a position followed by zero or more of any character, then "a" to "z".
- `(?=.*[A-Z])` — Match a position followed by zero or more of any character, then "A" to "Z".
- `(?=.*\d)` — Match a position followed by zero or more of any character, then a digit.
- `.{8,}` — Match 8 or more of any character.
- `$` — Anchor to the end of the input.

## Warnings

### Anchors match string ends, not line ends (info)

Without the m flag, ^ and $ match only the very start and end of the input — not the start and end of each line. On multi-line input this is often not what was intended.

**Fix:** Add the m flag if the pattern should apply per line.

## Details

- Capture groups: none

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Canonical URL: https://regex-explainer.gumballtools.com/regex/lookahead-password-validation
JSON API: `GET https://regex-explainer.gumballtools.com/api/v1/explain?pattern=...`
MCP endpoint: `https://regex-explainer.gumballtools.com/api/mcp`