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javascriptarraysstringprototype

Why are you unable to Array.prototype.pop.call() a string?

As far as I understood, some Array methods can be used on strings by using the call method. While coming up with an answer for this question:

Remove last forward slash from href anchor

I came across an issue I wasn't expecting. I couldn't use pop.apply() on a string without receiving this error;

"message": "Uncaught TypeError: Cannot delete property '39' of [object String]"

Why did this fail and why do only some array methods work?

let href = $('.anchor').prop('href');
Array.prototype.pop.call(href);

console.log(href);
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<a href="https://example.com/my-account/#example/" class="anchor">...</a>

Solution

  • Not all array methods can be used on array. Those methods which try to mutate the string won't work. In Javascript strings are immutable. So methods like push, pop, shift, splice don't work.