Google Tag Manager Parse Error. Primary Expression

问题

I am trying to save this Custom Javascript Variable within Google Tag Manager and return this error each time:

Error at line 2, character 4: Parse error. primary expression expected

var prodID = function pID() {
return document.querySelector(".no-display > input[name=product]").value;
}();

Can someone help me? I believe I have a primary expression.

回答1:

To fix the issue in Google tag manger, I simple re wrote the code to be :

function() {
  return document.querySelector(".no-display > input[name=product]").value;
}

回答2:

All code in a custom javascript variable should be within function() {}, or you will get this error.

Here's the documentation from Google:

This field should be a JavaScript function that returns a value using the 'return' statement. If the function does not explicitly return a value, it will return undefined and your container may not behave as expected. Below is an example of this field:

function() {
     var now = new Date();
     return now.getTime();   
}

来源：https://stackoverflow.com/questions/32418777/google-tag-manager-parse-error-primary-expression