如何在javascript中验证范围为5-20的数字？

Question

I tried like below

function isValidMobileNo(mobNo) {
    var pattern = /^\d{20}$/;
    return pattern.test(mobNo);
}

if (!isValidMobileNo(temp)) {
    $("#spanRegMobNo").html("Only Numbers allowed and limit is 5-20");
    return ("Only Numbers allowed and limit is 5-20" + "\n");

} else {
    $("#spanRegMobNo").html("");
    return "";
}

but here I have to enter 20 digits but where I want to give 5-20 range? so how?

Answer 1

Change your regex to

var pattern = /^\d{5,20}$/;

Use range to allow from 5 to 20 digits.

---

I'd also recommend to use the same regex on the input element on pattern attribute.

 input:valid { color: green; } input:invalid { color: red; } 

 <input type="text" pattern="\\d{5,20}" /> 

Answer 2

If you use HTML, you can use the input number tag.

<input type="number" name="quantity" min="1" max="5">

Else, in javascript, the pattern "/^\\d{5,20}$/" :)

Answer 3

Your question is not clear so here is 2 solutions for 2 cases.

If you don't want to use regex, you can also use this method(it's also check if it's a number-or string number like: "123" ):

This example will check if the number length is between 5 to 20:

function isValidMobileNo(mobNo) {
    var numLength = mobNo.toString().length;
    return (isNaN(mobNo) && numLength >= 5 && numLength <= 20);
}

This will check if the number range is between 5 to 20:

function isValidMobileNo(mobNo) {
    return (isNaN(mobNo) && mobNo >= 5 && mobNo<= 20);
}