The problem with type coercion is when it happens without you noticing it. You cannot "avoid" it...
You can avoid type coercion if you understand how the language works (aka strict equality in JavaScript) but this isn't something only in JavaScript land either.
I'll allow that there's inevitably some degree of opinion involved here, but I tend to agree with the parent poster that implicit conversion in languages like Javascript, PHP, and Perl is just another vector for bugs, and outweighs any of the advantages you get from having your language coerce everything for you. But then again, i'm one of those people that likes my language to force me to be very explicit about what I mean, so YMMV.
Regardless, the strict equality operator is not at all sufficient to avoid the dangers of JavaScript's implicit conversions. Pretty much _all_ the operators are going to coerce types for you, whether you meant for them to or not. For example, this function:
function increment(i) { return i + 1; }
Adds one to number right? But let’s say you’ve neglected to convert some user input in a form to a number as you should have done elsewhere in your code, and you end up calling increment("1"). This will return "11". So now you potentially have introduced a serious math error into your code you may not notice right away. Conversely, if you did this in Python, the function would have raised a TypeError immediately, because you can’t apply the arithmetic operator to two different types. You can’t just “avoid” type coercion in these loosely-typed languages by understanding the specifics of how it works, because you may not even know it’s happening until you start seeing unexpected results somewhere.
Python will throw an error. Ruby will throw an error. Tcl will throw an error. Erlang will throw an error. I believe most of the Lisps will throw an error.
What was it about "most dynamic languages"?
I should have changed my text to not say "regardless of definition" because you can do that in Python, Ruby, PHP, JavaScript, etc.
Python and Ruby support it through (star)args or default parameters
JavaScript supports it regardless
PHP supports it regardless
We can argue semantics or the fact that some of those types of errors can be caught with some subset of dynamic languages but I don't think that's useful.
My only point was when comparing a dynamic language with a static language I find variable function parameters to be one of the bigger issues over type coercion. But that's just, like, my opinion.