I am trying to test match a string if it is both singular and plural using javascript.
Because I need to use a variable I'm using RexExp like so but it's always returning true even if I use checksxcd or anything else, as long as check is there it passes.
let str = 'check'
let reg = new RegExp("(["+ str +"])(s\\b|\\b)", "g");
reg.test(check)
// Returns true
If I test this without using the str variable it works for only singluar and only plural of the word check as expected.
let reg = new RegExp(/([check])(s\b|\b)/, "g");
I'm assuming I have a syntax issue but I can't seem to find out what I'm doing wrong. Any help is appreciated.
You are using str in the regex and are running the check against the str string. That is why the result will always be true.
You can use
let str = 'checkl'
let reg = new RegExp("\\b"+ str + "(?:e?s)?\\b")
console.log(reg.test("A check")) // => false
console.log(reg.test("A checkl")) // => trueDo not use g flag when using a regex in RegExp#test, that may lead to unexpected results.
Note I added an optional e before s ending, since the noun endings can be es or s.
Pattern details:
\b - a word boundarystr - the str word(?:e?s)? - an optional sequence of an optional e and then s (so it is either s or es or empty string)\b - a word boundary.