CODEWITHSUNDEEP
javascriptfunction
GPraz
GPraz

Reputation: 308

SyntaxError: missing ( before formal parameters

I was trying to implement recaptcha on my website, so I created a callback function using javascript which should be executed when a user submits a successful captcha response:

<script>
   function onSubmit = function(token) {
      document.getElementById("form-signin").submit();
   }
</script>

But always got this error SyntaxError: missing ( before formal parameters when using Firefox.

When using Google Chrome, I got this error instead: Uncaught SyntaxError: Unexpected token =

Both browsers indicate that the error is located at function onSubmit = function(token) {, but I don't know why this happened.

Can anyone be so kind as to tell me what is wrong?

Upvotes: 3

Views: 9003

Answers (2)

Quentin
Quentin

Reputation: 943220

function some_identifier can start either a function declaration or a function expression. Either way, the next characters must be ( then any argument definitions, then ).

If you want to assign the result of evaluating a function expression to a variable, as you are trying to do here, then you must declare the variable in the normal way (i.e. with the var keyword, unless you have declared it already, or are not using strict mode and want to create a global).

So either:

function onSubmit(token) {
  document.getElementById("form-signin").submit();
}

or

var onSubmit = function(token) {
  document.getElementById("form-signin").submit();
}

Upvotes: 2

Aurel B&#237;l&#253;
Aurel B&#237;l&#253;

Reputation: 7963

There are two basic ways to declare a named function:

function onSubmit(token){
    document.getElementById("form-signin").submit();
}

Or:

var onSubmit = function(token){
    document.getElementById("form-signin").submit();
};

In your case, just go with the first.

Upvotes: 2

Related Questions