JavaScript error: "val.match is not a function"

Question

I’m using the match function with a Regular Expression.

The code I’m using is:

if(val.match(/^s+$/) || val == "" )

However, it produces the following error:

"val.match is not function"

What is the problem?

Can we see where you have defined val? Make sure val is a string: val.toString(). Or you can use Regex.exec to implicitly convert to a string: /^s+$/.exec(val). — user236139
– user236139, Commented Feb 3, 2011 at 5:07
the val is string, just now i checking the match is working for some word and not working the some word, — zahir
– zahir, Commented Feb 3, 2011 at 5:19
Definitely make sure val is defined and a String. Also, I'm guessing it's a typo that you don't have a slash before the 's' in your regex. If that is the case you can replace your if test with "if(val.match(/^\s*$)" — Eric Wendelin
– Eric Wendelin, Commented Feb 3, 2011 at 5:35
Thanks for the idea Mr. Eric Wendelin, I just changed the coding like to val.toString(), that is working, i am new to javascript, if any drouble for ur work, sorry, thanks eric — zahir
– zahir, Commented Feb 3, 2011 at 5:50
Seems like this has been answered - would be nice to see Eric get the credit. Care to add it as an answer? — johnhunter
– johnhunter, Commented Feb 25, 2011 at 11:37

Rifky Niyas · Accepted Answer · 2022-02-21 14:25:04Z

90

I would say that val is not a string.

I get the

val.match is not function

error for the following

var val=12; 
if(val.match(/^s+$/) || val == ""){
   document.write("success: " + val);
}

The error goes away if you explicitly convert to a string String(val)

var val=12; 
if(String(val).match(/^s+$/) || val == ""){
   document.write("success: " + val);
}

And if you do use a string you don't need to do the conversion

var val="sss"; 
if(val.match(/^s+$/) || val == ""){
   document.write("success: " + val);
}

edited Feb 21, 2022 at 14:25

Rifky Niyas

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answered Mar 4, 2011 at 16:47

chrisp7575

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2 Comments

Mark Stewart Over a year ago

Thanks! I was using the code at stackoverflow.com/questions/881085/… and was getting the "is not a function" message and was going crazy!

robivictor Over a year ago

if you need this to implement some sort of pipe transform, it is a good idea to convert the incoming values to string to make sure it works all the time. Thanks @chrisp7575

skipper · Accepted Answer · 2014-12-23 19:16:32Z

23

the problem is: val is not string

i can think of two options 1) convert to string: might be a good option if you are sure val has to be string

"Same as above answer"

var val=12; 
if(String(val).match(/^s+$/) || val == ""){
   document.write("success: " + val);
}

2) skip the line: in my case, it was better to just check the val type and skip if it is not string, because it was not a good idea to run "match" function anyways.

val = 12;
if( val.match) {
  if(val.match(/^s+$/) || val == "" ) {
    document.write("success: " + val);
  }
} else {
    document.write("not a string: " + val);
}

answered Dec 23, 2014 at 19:16

skipper

2812 silver badges4 bronze badges

Comments

Eric Wendelin · Accepted Answer · 2011-03-11 18:46:50Z

5

NOTE: making this an answer as suggested above from my comment.

Definitely make sure val is defined and a String. Also, I'm guessing it's a typo that you don't have a slash before the 's' in your regex. If that is the case you can replace your if test with "if(val.match(/^\s*$)"

answered Mar 11, 2011 at 18:46

Eric Wendelin

44.6k9 gold badges73 silver badges94 bronze badges

1 Comment

Benjiro Over a year ago

I have a similar issue, in my case, I am validating that the value is a number and not an alphabet, will converting it to string be a good idea? because when I do, the validation fails and returns an object instead of either string(error message) or boolean.

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