Nodejs Object Declaration And Immediate Shorthand If Statement Crashes The App

Can anyone give a comprehensive reason as to why the following node.js script would be crashing? var _ = require('underscore'); var foo = { bar: 123 } (!_.isNull(foo.bar)?foo.b

Solution 1:

Automatic semicolon insertion has hit you.

Your code is interpreted as

var foo = {
  bar: 123
}(   !_.isNull(foo.bar)?foo.bar = true:""  );

which is a function call in an assignment. Even before you would get an error that {bar:123} is not a function, you are getting an exception because you are accessing a property on foo before it is assigned a value to (and is still undefined).

To fix this, use

var foo = {
  bar: 123
};

!_.isNull(foo.bar)?foo.bar = true:"";

(where both the semicolon and omitting the parenthesis would have fixed the issue alone).

Solution 2:

Problem is here:

(!_.isNull(foo.bar)?foo.bar = true:"");

That statement makes no sense, and I don't think you can assign a property inside the inline if statement. I also don't know why you're trying to overwrite 123 with true.

Be that as it may, what you seem to be trying to do should be accomplishable by this:

foo.bar = (!_.isNull(foo.bar) ? true : "");