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javascript, best way to tell if a val is a single digit

rated 0 times [ 26] [ 2] / answers: 1 / hits: 19771 / 14 Years ago, fri, october 1, 2010, 12:00:00

whats the best way to tell if a value in javascript is a single digit. Ive been doing something like

var valAsString = '' + val;

if (valAsString.match(/d/) {}

clarification: I mean one of 0,1,2,3,4,5,6,7,8,9

Also, should what I have work? Im surprised how many different ways people are coming up with for this.

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donaldcristianl

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1 Year ago

answered 14 Years ago reed · Accepted Answer

The /d/ regexp will match a digit anywhere on a string, for example in foo1 will match 1.

For a regexp approach need something like this, to ensure that the string will contain a single digit:

if (/^d$/.test(val))  {

  //..

}

Note that I'm using the test method, which is recommended when you only want to check if a string matches the pattern, also, the test method internally will convert to sting the argument.

Another short non-regexp approach:

function isDigit(val) {

  return String(+val).charAt(0) == val;

}