How to validate input fields ensuring specific string patterns in Javascript

Question

Trying to validate if the user has entered a name starting with a letter, is at least 8 characters long, and has at least one number in it. See the code below:-

The first two conditions I have been able to make work, its validating whether or not there's a number within. I have tried to run a function all by itself with just the number validation in it but I cant seem to get it to work. this is my latest attempt to make it work, any help would be greatly appreciated, keep in mind I am a first year student :)

function nameVerify() {

    var char1;
    var char2;
    var index;
    var NL = "\n";
    var valid = false;


    char1 = useNam.substr(0, 1);
    char1 = char1.toUpperCase();
    char2 = useNam.substr(1);

    for (index = 1; index <=useNam.length; index++){        
    while (!valid) {

    if ((char1 <"A" || char1 >"Z") || (useNam.length <8) && (char2 >=0 || char2 <=9)){
        alert("alert 1");
        useNam = prompt("prompt 2");
        char1 = useNam.substr(0, 1);
        char1 = char1.toUpperCase();
        char2 = useNam.substr(1);           


        }

    else {
        valid = true;
        alert("Congragulations, you entered it correctly");
    }
    }
    }}

var useNam;

useNam = prompt("prompt 1");
result = nameVerify(useNam);

It would be better to use regex for this type of validation... — brso05
– brso05, Commented Nov 11, 2014 at 20:20
It's probably easier than you think -> jsfiddle.net/adeneo/pwnnct8d — adeneo
– adeneo, Commented Nov 11, 2014 at 20:22
Thanks for all the help guys :). I'll do my best to apply one of these to my code, much appreciated :) — ROYDENSTORM
– ROYDENSTORM, Commented Nov 11, 2014 at 22:22

ryanve · Accepted Answer · 2014-11-11 21:08:19Z

2

/**
 * @param {string} str name to test
 * @return {boolean} true if str is valid
 */
function isValidName(str) {
  return /^[a-zA-Z][a-zA-Z0-9]{7,}$/.test(str) && /\d/.test(str)
}

/^[a-zA-Z][a-zA-Z0-9]{7,}$/ tests that it starts with a letter, is at least 8 characters long, and all characters are letters or numbers. /\d/ tests that it contains at least 1 number. See MDN's RegExp documentation for reference in particular about the special characters and the x{n,} syntax described there. If you allow underscores too then you could use /^[a-zA-Z]\w{7,}$/ for the first test.

edited Nov 11, 2014 at 21:08

answered Nov 11, 2014 at 20:37

ryanve

52.9k33 gold badges107 silver badges142 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Simon H · Accepted Answer · 2014-11-11 20:24:05Z

0

Try this

valid = myString.match(/\d/).length > 0

This is a regex and will return the first number it matches or an empty array otherwise

answered Nov 11, 2014 at 20:24

Simon H

21.2k14 gold badges84 silver badges144 bronze badges

Collectives™ on Stack Overflow

How to validate input fields ensuring specific string patterns in Javascript

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related