如何知道正则表达式是否在使用量词设置的字符大小限制的下限或上限上失败

Question

Quantifiers can be used in regular expressions to match strings within a size limit:

"54 343 2356 2".match(/\d{3,4}/)  // 343, 2356

If I wanted to test a string against a regex with a quantifier, how would I know if the test failed on the lower or upper bound of the character size limit?

/\d{3,4}/.test("54525")

Answer 1

if the test failed on the lower or upper bound of the character size limit?

For that you don't need regex, Instead do an if-else conditioning , So count number of digit in that number:

 let x = "54525"; if (x.length < 3) { console.log(x + ' has less digits than 3'); } else if (x.length > 4) { console.log(x + ' has more digits than 4'); } else { console.log(x + ' has exactly number of digits between 3 or 4'); }