Different javascript interpreter behavior in Chrome and Firefox?

M

mobileDeveloper2014-08-27 15:01:01

JavaScript

mobileDeveloper, 2014-08-27 15:01:01

A colleague accidentally stumbled upon the following difference in how browsers work. The latest versions are being used.
The code:

<html>
    <head>
        <script>
            function test() {
                functionExpressionOrFunctionDeclaration();
                
                if (true) {
                    function  functionExpressionOrFunctionDeclaration()  {
                        console.log('run');
                    }
                }
            }
            
            test();
        </script>
    </head>
</html>

Chrome will output 'run'.
Firefox (IE11 too) will throw 'ReferenceError: functionExpressionOrFunctionDeclaration is not defined'.
The documentation https://developer.mozilla.org/en-US/docs/Web/JavaS... says why this happens.

"A function declaration is very easily (and often unintentionally) turned into a function expression."

I always thought that in this case the behavior of Chrome is correct, but now I doubt it, and I could not find an answer in the ECMAScript specification.
Which browser is behaving correctly?

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4 answer(s)

L

Lynn "Coffee Man", 2014-08-27
@mobileDeveloper

Here it is broken down in detail.
dmitrysoshnikov.com/ecmascript/en-chapter-5-functi...
Formally, both are right, because this situation is not defined by the standard

E

Evgeny Petrov, 2014-08-27
@Petroveg

I am on the side of FF in the issue of the impossibility of the appearance of FD in the block of instructions. If it's called a statement block, then the declaration doesn't belong there.

M

mobileDeveloper, 2014-08-27
@mobileDeveloper

@Lynn gave the correct link to Dmitry Soshnikov, only I can't select his comment as the correct answer.

A

Alexander Keith, 2014-08-27
@tenbits

Here for similar things also there is "use strict". With it, you will get a "SyntaxError" since a function declaration cannot be in statement blocks.