I have the following regex expression that validates via jquery a textbox element in html.
/^-?\d*[.]?\d*$/
I would like to alter this so that the decimal point can only be added if it has a leading number before it.
If someone could provide me the solution I'd be very grateful.
Just add + quantifier after first \d
^-?\d+[.]?\d*$
const n1 = '.1';
const n2 = '0.1';
const n3 = '-0.1';
const regex = /^-?\d+[.]?\d*$/;
console.log(`${n1} ==> ${regex.test(n1)}`);
console.log(`${n2} ==> ${regex.test(n2)}`);
console.log(`${n3} ==> ${regex.test(n3)}`);Above pattern will match strings that have no digits after the decimal such as "1.". If you want to enforce digits after decimal if decimal is present, use following regex
^-?\d+(\.\d+)?$
const n1 = '1.';
const n2 = '1.1';
const regex = /^-?\d+(\.\d+)?$/;
console.log(`${n1} ==> ${regex.test(n1)}`);
console.log(`${n2} ==> ${regex.test(n2)}`);