regex - regular expression for number and decimal points in javascript - Stack Overflow

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I have checked the below link for regular expression

Regex to match 2 digits, optional decimal, two digits

regular expression should accept whole number or decimal points. max length should be 10 numbers before decimal and 4 digits after decimal.

tried this below code from above link (2 digit decimal point)

\d{0,2}(\.\d{1,2})?

var patt =new RegExp("\d{0,2}(\.\d{1,2})?")
undefined
patt.test(1)
true
patt.test(1.1)
true
patt.test(11)
true
patt.test(111.111)
true

for 3 digits after decimal also it is giving true value, which is invalid.

I have checked the below link for regular expression

Regex to match 2 digits, optional decimal, two digits

regular expression should accept whole number or decimal points. max length should be 10 numbers before decimal and 4 digits after decimal.

tried this below code from above link (2 digit decimal point)

\d{0,2}(\.\d{1,2})?

var patt =new RegExp("\d{0,2}(\.\d{1,2})?")
undefined
patt.test(1)
true
patt.test(1.1)
true
patt.test(11)
true
patt.test(111.111)
true

for 3 digits after decimal also it is giving true value, which is invalid.

• javascript
• regex

Share Improve this question Follow edited May 23, 2017 at 12:15 CommunityBot 111 silver badge asked Aug 25, 2016 at 6:46 SivaRajiniSivaRajini 7,3752222 gold badges8484 silver badges129129 bronze badges 4

• 1 Your regex shorthand classes should be escaped with double backslashes and the current /d{0,2}(.d{1,2})?/ expression matches an empty string, so the result is always true. – Wiktor Stribiżew Commented Aug 25, 2016 at 6:50
• @Wiktor It might be a duplicate but not of that question. See my answer. – jedifans Commented Aug 25, 2016 at 6:52
• @jedifans: I agree I was too quick, but your answer does not seem to answer the question correctly. – Wiktor Stribiżew Commented Aug 25, 2016 at 6:54
• I have updated to include both a fix for the given code and the requirement for 10 digits, etc. – jedifans Commented Aug 25, 2016 at 7:00

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4 Answers 4

Sorted by: Reset to default 9

You have to use delimiters, to determine where your match starts and where it ends. And you say max length should be 10 numbers before decimal and 4 digits after decimal so your limits are incorrect too:

var patt = /^\d{1,10}(\.\d{1,4})?$/;

var patt = new RegExp(/^\d{1,10}(\.\d{1,4})?$/);

console.log( patt.test(1) );                // true
console.log( patt.test(1.1) );              // true
console.log( patt.test(11.11) );            // true
console.log( patt.test(111.111) );          // true
console.log( patt.test(1111.1111) );        // true
console.log( patt.test(1111111111.1111) );  // true

console.log( patt.test(111.11111) );        // false, because to long after decimal
console.log( patt.test(11111111111.1111) ); // false, because to long before decimal

Or as suggested here, not using RegExp and instead use a literal. There could be support issues with RegExp in some browsers. The output is the same, so better use this solution:

var patt = /^\d{1,10}(\.\d{1,4})?$/;

console.log( patt.test(1) );                // true
console.log( patt.test(1.1) );              // true
console.log( patt.test(11.11) );            // true
console.log( patt.test(111.111) );          // true
console.log( patt.test(1111.1111) );        // true
console.log( patt.test(1111111111.1111) );  // true

console.log( patt.test(111.11111) );        // false, because to long after decimal
console.log( patt.test(11111111111.1111) ); // false, because to long before decimal

The regex doesn't say the string should end with the last character, or start with the first one. Try:

var patt = /^\d{1,2}(\.\d{1,2})?$/;

For your 10 digits before and 4 digits after requirement:

var patt = /^\d{1,10}(\.\d{1,4})?$/;

Why don't you just check:

 input < Math.pow(10,10) && input % Math.pow(10,-4) == 0

here is the code that is working for me

 function IsValidNumericCode(number,messageDiv,msg){
 var reNumeric = /^\d*[0-9](|.\d*[0-9]|,\d*[0-9])?$/;
 var result  = reNumeric.test(number); if(!result){ messageDiv.html(msg);
 messageDiv.fadeIn(400).fadeOut(400).fadeIn(400).fadeOut(400).fadeIn(400);
 }else{ messageDiv.html('');} return result;

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