Regex match any characters prefixed with a string and specific length in JavaScript

Question

I need to write a JavaScript program where it validates input.

Requirement:

• Input will have a specific prefix. (eg: --NAME--)
• After this prefix, there can be any characters. (eg: --NAME--any-name_wit#-any*_special_char@#$%)
• Minimum length of total input (or length of suffix) should be 50 (for example)

I was able to write regex for the first two points, but I couldn't include the final point. here is what I have tried for the first two points.

input.match(^--NAME--(.*)$)

Answer 1

You can use a lookahead assertion for length:

/^(?=.{50})--NAME--.*$/

From start, at least 50 characters, starting with --NAME--.

Answer 2

Use pattern /^--NAME--.{42,}$/

.{42,} - This will match 42 or more characters. The total will be 50 including the prefix (--NAME--).

const regex = /^--NAME--.{42,}$/

console.log(regex.test("--NAME--C$#V"))
console.log(regex.test("--NAME--C$#Vf34F#$f3ftbalc93h34vs#$3gfsddn;yu67u4g3dfvrv34f3f3ff"))

Demo in regex101.com