How to validate for Values "0" or "00" or "000" for textfield which has the regex and some accepted values

var myregex = /^[0-9][0-9]{0,3}$|^[0-9][0-9]{0,3}[\.][0-9]$/;
if(!myregex.test($('#txt1').val()) || $('#txt1').val()=="0"){
    alert("Please Enter Correct value");
}

Now My mandatory things are it should

1. follow Regex
2. we should not able to enter the value "0" or "00" or "000"

So my above if() raises an alert if the user enter a "0" and if we enter "00" or "000" or "0000" it doesnot catch it .But if we enter "00000" it catches it due to regex. How can i handle for 2,3,4 zeros .Now Here I ca开发者_高级运维n put a regex which doesnot accept zeros such as this one "/^[^0].*$/" but My textfield should Accepts this values as right (0.2,0.3,0.4) .so i cannot use this regex.

Avoid regex, it's a nightmare to get exactly right, and to maintain in the future. Instead, use built-in JS string parsing functionality:

var val = parseFloat($('#txt1').val());
if (isNaN(val) || (val === 0))
{
    alert("Please Enter Correct value");
}

/^[1-9]\d{0,3}(?:\.\d)?$|^0\.[1-9]$/

The first alternative matches any number from 1.0 to 9999.9. The first digit has to be at least 1, which eliminates leading zeroes. The fraction part is optional ((?:\.\d)?), so it also matches integers from 1 to 9999. The second alternative handles the special cases of 0.1 through 0.9.

It looks like your regular expression requires 0 through 9999, or 0.0 through 9999.9, but you do not want to accept a 0 alone, or a series of zeros.

If that's the case, I'd say use something similar to ken's answer and process it as a float, then check that the float is above 0 and below 9999.9:

var val = parseFloat($("#txt1").val());
if(isNan(val) || val <= 0 || val > 9999.9) {
    alert("Please enter a value between 0 and 9999.9");
}

If you need to use your regex and just add a check that the string doesn't consist entirely of zeroes, you can add a negative lookahead expression: (?!0+$) and enclose the alternation in a non-capturing group:

/^(?!0+$)(?:[0-9][0-9]{0,3}|[0-9][0-9]{0,3}[\.][0-9])$/

No need for Regex or any of that, quite simple.

if(('#txt1').val() < 0.1 ){
    alert("Please Enter Correct value");
}

There you go, problem solved