Comments (2)
First, I want to explain why such an error would be thrown. Basic JavaScript data types all have a method named toString()
. It's important to note that each method pertains to one class (Function, String, Number or Object) and only handles their kind.
So this works:
> Function.prototype.toString.call(function myFunction() {})
"function myFunction() {}"
But this doesn't:
> Function.prototype.toString.call({})
Uncaught TypeError: Function.prototype.toString is not generic(…)
How could this happen when not forcing it with call
, like in the code above? (thing.toString()
) Well, through somewhat strange inheritance or method assignment:
> var a = {};
> a.toString = Function.prototype.toString;
> a.toString()
Uncaught TypeError: Function.prototype.toString is not generic(…)
You may want to check why you have objects with a broken toString()
method.
In any case, we'd rather not have the debugger break on any object no matter how broken its toString()
method is, so running it inside a try/catch is indeed a good idea.
Instead of calling toString()
twice, with only the first call guarded, I suggest replacing it by a safe function that cannot fail:
function safeToString(thing) {
try {
return thing.toString();
} catch (e) {
return "[toString failed]";
}
}
...
if (coercedObj !== Window.prototype && "toString" in coercedObj
&& safeToString(coercedObj) == "[object Window]") { ...
from knockout-es5.
Thanks for the good catch there.
from knockout-es5.
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