regular expression in javascript

Question

I'm trying to get it so that the alert message pops up if the value entered into the textBox is not a decimal number between 0.0 and 4.9 with just one digit before and after the decimal, but the message pops up regardless of what number I entered and I think there's something wrong with my regular expression but I can't figure it out.

if ((textBox.value.search("/^[0-4]\\.[0-9]$/")) == -1) {
    alert("Invalid Entry");
    return false;
}

The return false is there since if the number is invalid then the function will exit.

keeganwatkins · Accepted Answer · 2012-06-17 19:39:01Z

1

You could also do this without using a RegExp, by parsing the value to number via parseFloat and checking the result via isFinite.

// Parse the value as a float. If the value cannot be parsed,
// `parseFloat` will return NaN    
var toFloat = parseFloat( textBox.value );

// Use `isFinite` to verify that parsing was successful. If it
// was, just check the range (i.e. between 0 and 4.9)
if ( isFinite( toFloat ) && toFloat >= 0 && toFloat <= 4.9 ) {
    // Input is valid
} else {
    // Input is invalid
}

hope that helps. cheers!

answered Jun 17, 2012 at 19:39

keeganwatkins

3,6961 gold badge16 silver badges12 bronze badges

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

Comments

bjornd · Accepted Answer · 2012-06-17 19:08:16Z

0

It should be:

if ((textBox.value.match(/^[0-4]\.[0-9]$/))) {
    alert("Invalid Entry");
    return false;
}

Here you aren't interested in the position of match but only in the fact of matching so it isn't necessary to use search, match is enough.

answered Jun 17, 2012 at 19:08

bjornd

23k4 gold badges59 silver badges74 bronze badges

Collectives™ on Stack Overflow

regular expression in javascript

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related