Regular expression that allows alphanumeric characters and spaces, but does not permit spaces at the beginning or end of the

Question

Regular expression that allows alphanumeric characters and spaces, but does not permit spaces at the beginning or end of the

I need to create a regular expression that allows for a combination of letters, numbers, and spaces within a word, ranging in length from 3 to 50 characters, but without spaces at the beginning or end of the string. Here is the regex pattern I have come up with:

/^[^-\s]([a-z0-9]|[a-z0-9\s-]){3,50}[^-\s]+$/i

Examples of valid strings:

uma
umair
umair K

Examples of invalid strings:

 uma
u
um
umair

The last example contains a trailing space, making it invalid.

javascript regex spaces alphanumeric

Answer 1

Answer №1

^(?=.{3,50}$)[^\W_]+(?: [^\W_]+)*$

^ Start the string
(?=.{3,50}$) Looking ahead, there should be between 3 and 50 characters before the end of the line
[^\W_]+ Match any word character except _ one or more times
(?: [^\W_]+)* Match a space followed by one or more word characters, any number of times
$ End the string

var r = /^(?=.{3,50}$)[^\W_]+(?: [^\W_]+)*$/
var a = [
  'uma','umair','umair K', //valid
  ' uma','u','um','umair ' //invalid
]

a.forEach(function(s){
  console.log(r.test(s) ? `Valid: ${s}` : `Invalid: ${s}`)
})

Alternatives:

^[^\W_][a-zA-Z\d ]{1,48}[^\W_]$

Answer 2

^(?=.{3,50}$)[^\W_]+(?: [^\W_]+)*$

^ Start the string
(?=.{3,50}$) Looking ahead, there should be between 3 and 50 characters before the end of the line
[^\W_]+ Match any word character except _ one or more times
(?: [^\W_]+)* Match a space followed by one or more word characters, any number of times
$ End the string

var r = /^(?=.{3,50}$)[^\W_]+(?: [^\W_]+)*$/
var a = [
  'uma','umair','umair K', //valid
  ' uma','u','um','umair ' //invalid
]

a.forEach(function(s){
  console.log(r.test(s) ? `Valid: ${s}` : `Invalid: ${s}`)
})

Alternatives:

^[^\W_][a-zA-Z\d ]{1,48}[^\W_]$

Answer 3

Answer №2

This is how a direct translation of the given requirements would appear:

!/[^a-zA-Z\d\s]/.test(str) &&
str.length >= 3 && str.length <= 50 &&
!/^\s/.test(str) &&
!/\s$/.test(str))

Is it really necessary to combine everything into a single regular expression?

Answer 4

This is how a direct translation of the given requirements would appear:

!/[^a-zA-Z\d\s]/.test(str) &&
str.length >= 3 && str.length <= 50 &&
!/^\s/.test(str) &&
!/\s$/.test(str))

Is it really necessary to combine everything into a single regular expression?

Regular expression that allows alphanumeric characters and spaces, but does not permit spaces at the beginning or end of the

Answer №1

Answer №2

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