I'm trying to match a string that numbers cannot follow characters
For example, these should all match:
- abc-123
- 123-abc
- 123-abc-123
- abc-123-abc
not match:
- abc123
- 123abc
- abc1
- a1b2
Please help me to find a javascript regex.
CodePudding user response：
To match strings that contain only letters separated by numbers, you can use the following regular expression:
/^[a-zA-Z] (?:-[a-zA-Z] )*$/
This regular expression will match strings that start and end with letters, and have a number in between. The letters and the number must be separated by a hyphen.
For example, you can use the following code to test this regular expression:
const regex = /^[a-zA-Z] (?:-[a-zA-Z] )*$/;
console.log(regex.test("abc-123")); // should return true
console.log(regex.test("123-abc")); // should return true
console.log(regex.test("123-abc-123")); // should return true
console.log(regex.test("abc-123-abc")); // should return true
console.log(regex.test("abc123")); // should return false
console.log(regex.test("123abc")); // should return false
console.log(regex.test("abc1")); // should return false
console.log(regex.test("a1b2")); // should return false
This code defines a regular expression using the pattern described above, and then uses the test method to check if various strings match the pattern. The test method returns a boolean indicating whether the string matches the pattern or not.
Edited, since the question changed (I am still not sure if it is correct).
CodePudding user response：
Assuming the following requirements:
- alternating between letters and digits separated by hyphen
- must not start or end with a hyphen, e.g.:
abc-123-not valid - if no hyphen, either only letters or digits:
abcor123are valid
By matching the sequence and making everything optional. > regex101 demo
^\b\d*(?:\b-?[a-z] -\d )*-?\b[a-z]*$
Or by use of lookaheads to disallow \d-\d or [a-z]-[a-z]. > regex101 demo
^(?:\d -?\b(?!\d)|[a-z] -?\b(?![a-z])) $
In both variants the optional hyphen is required between due the word boundary.