Javascript "Uncaught TypeError: object is not a function" associativity question

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Code is as follows:

    <a href="javascript:;" id="test">hello</a>

<script type="text/javascript">
    document.getElementById("test").addEventListener("click", function () {
    }, false)
    function test() {
      var postTypes = new Array('hello', 'there')   
      (function() { alert('hello there') })()

This will throw an:

"Uncaught TypeError: object is not a function"

If I wrap the anonymous function call/invocation in another set of parentheses it will execute the alert, but still give me an error. If I put a semi-colon after the "var postTypes" definition then it will completely fine.

I was led to believe that javascript does not require semi-colons, so I'm making a guess that there is some weird associativity rules of function application that I am not fully understanding. Why am I getting this error?

JavaScript does require semicolons, it's just that the interpreter will insert them for you on line breaks where possible*.

Unfortunately, the code

var a = new B(args)(stuff)()

does not result in a syntax error, so no ; will be inserted. (An example which can run is

var answer = new Function("x", "return x")(function(){return 42;})();

To avoid surprises like this, train yourself to always end a statement with ;.

* This is just a rule of thumb and not always true. The insertion rule is much more complicated. This blog page about semicolon insertion has more detail.

JavaScript Tutorial, JavaScript (JS) is a lightweight, interpreted, or just-in-time compiled programming language with first-class functions. While it is most well-known as the scripting  JavaScript? Begin learning here by typing in your first name surrounded by quotation marks, and ending with a semicolon. For example, you could type the name "Jamie"; and then hit enter.

Your code experiences a case where the Automatic Semicolon Insertion (ASI) process doesn't happen.

You should never rely on ASI. You should use semicolons to properly separate statements:

var postTypes = new Array('hello', 'there'); // <--- Place a semicolon here!!

(function() { alert('hello there') })();

Your code was actually trying to invoke the array object.

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I got a similar error and it took me a while to realize that in my case I named the array variable payInvoices and the function also payInvoices. It confused AngularJs. Once I changed the name to processPayments() it finally worked. Just wanted to share this error and solution as it took me long time to figure this out.

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Try to have the function body before the function call in your JavaScript file.

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I was getting this same error and spent a day and a half trying to find a solution. Naomi's answer lead me to the solution I needed.

My input (type=button) had an attribute name that was identical to a function name that was being called by the onClick event. Once I changed the attribute name everything worked.

<input type="button" name="clearEmployer" onClick="clearEmployer();">

changed to:

<input type="button" name="clearEmployerBtn" onClick="clearEmployer();">

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JavaScript Courses & Tutorials, JavaScript is a lightweight, interpreted programming language. It is designed for creating network-centric applications. It is complimentary to and integrated with  When comparing a string with a number, JavaScript will convert the string to a number when doing the comparison. An empty string converts to 0. A non-numeric string converts to NaN which is always false. When comparing two strings, "2" will be greater than "12", because (alphabetically) 1 is less than 2.

The Modern JavaScript Tutorial, JavaScript attempts to convert the string numeric literal to a Number type value. First, a mathematical value is derived from the string numeric literal. Next, this value is rounded to nearest Number type value. If one of the operands is Boolean, the Boolean operand is converted to 1 if it is true and +0 if it is false.

What Is JavaScript? A Guide for Total Beginners, JavaScript – Equality (==) vs. Identity (===) Operators By Lokesh Gupta | Filed Under: JavaScript If you have worked on javascript then you must have noticed these two operators to compare values.

  • Looks almost like you are trying to create both an anonymous function and static function and expecting it to execute as one. What happens if you remove function()
  • Or: To avoid surprises like this, train yourself to write clean readable code (which should always apply) and know the general ASI rules... it really is no different than "knowing" how closures in JS work.
  • One way to fix the issue, but I can't get behind the Crockford-club.
  • @pst: Let me rephrase, I'm not in the Crock's-club at all :)
  • In that case I apologize for the harsh words :(
  • I did enjoy the quiz. ASI is indeed terribly confusing with icky-code!
  • Same here, I had a variable named alert and was trying to call the javascript alert function and it would say 'alert is not a function'. It was trying to call the alert variable instead of the actual function