CODEWITHSUNDEEP
javascriptregex
Ali Azim
Ali Azim

Reputation: 180

Javascript match a string which start with a specific char from the set of chars and end with same char using Regular Expression

I need to achieve a particular task in javascript, in which my goal is to match the string which starts with a char from a specific set of characters like vowel and ends with the same character where the length of the string is greater than three.

so far I have done the following code that starts and ends with the same character but doesn't know how to specify it that the first char is from the specific set of character:

function regexVar() {

    var re = /(.).*\1/
    return re;
}

console.log("obcdo".test(s));

let suppose the specific set of chars is the vowel

(a, e, i, o, u)

in this case:

abcd ----> false

obcdo ----> true

ixyz ----> false

Upvotes: 2

Views: 2058

Answers (4)

white shadow
white shadow

Reputation: 11

function regCheck(string){

    let re = new RegExp(/^(a|e|i|o|u).*\1$/g);
    return re.test(string);

}
regCheck('aewxyzae')

Upvotes: 0

Rishu Ranjan
Rishu Ranjan

Reputation: 574

If we are taking the set of vowels then,the regular expression for words beginning and ending with the same vowel is:

var re = /(\ba(\w+)a\b|\be(\w+)e\b|\bi(\w+)i\b|\bo(\w+)o\b|\bu(\w+)u\b)/g;

Upvotes: 0

CertainPerformance
CertainPerformance

Reputation: 370729

You need to use a character set to ensure the captured character is one of the ones you want, backreference the first captured group at the end of the pattern, not the third group (your pattern doesn't have 3 capture groups), use ^ and $ to anchor the pattern to the start and end of the string, and repeat with {2,} rather than * to make sure the whole string is at least 4 characters long:

/^([aeiou]).+\1$/


const re = /^([aeiou]).{2,}\1$/
console.log(
  re.test('abcd'),
  re.test('obcdo'),
  re.test('ixyz')
);

Upvotes: 3

Code Maniac
Code Maniac

Reputation: 37755

You can use this pattern

/^([aeiou]).+\1$/i
  • ^ - Start of string
  • ([aeiou]) - Matches a,e,i,o,u any one of that. (group 1)
  • .+ - Match anything except new line.
  • \1 - Match group 1
  • $ - End of string

let startAndEnd = (str) =>{
  return /^([aeiou]).+\1$/i.test(str)
}

console.log(startAndEnd(`ixyz`))
console.log(startAndEnd(`abcd`))
console.log(startAndEnd(`obcdo`))

Upvotes: 0

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