JavaScript Function Declaration Ambiguity

Is there an explanation of all of them? And, if the "regular" function declaration is really that "fragile" and can be easily override by the function object with same name, should I stay away from that?

These functions are made members of the window object, they are in effect declared globally. If you assign a local variable to a value of a function, then that local variable takes precedence over members in the window object. If javascript can't find a local variable, it searches up in scope to find it, the window object being the last resort. That's what happened in your last example, it has a variable say that is in a more specific scope than the global function say.

Download File 🔥 https://urlca.com/2xYdF9 🔥

that is a direct call of a function expression. The parser recognizes the statement as a function declaration and then fails when it finds the parentheses after the function body. The reason is that function declarations are recognized with most precedence to avoid the ambiguity with function expressions.

because the variableStatement production contains functionExpression as a descendant, which leads to an ambiguity. The parser cannot choose among functionDeclaration and functionExpression because they are almost equal:

The statement in question thus is invalid per the above restriction, though in fact it is not ambiguous by productions of the grammar: as it omits the function identifier, it cannot be a functionDeclaration. A statement exposing the syntactic ambiguity would be

Note: An expression statement cannot begin with the keyword function to avoid ambiguity with a function declaration. The function keyword only begins an expression when it appears in a context that cannot accept statements.

A function expression is very similar to, and has almost the same syntax as, a function declaration. The main difference between a function expression and a function declaration is the function name, which can be omitted in function expressions to create anonymous functions. A function expression can be used as an IIFE (Immediately Invoked Function Expression) which runs as soon as it is defined. See also the chapter about functions for more information.

I think people do in general not expect live bindings at all. Fordeclarations and the purpose of initialisation order, yes, but not formutable variables. You should export consts.See alsostackoverflow.com/q/35223111/1048572?what-is-the-difference-between-importing-a-function-expression-or-a-function-declaration-from-a-ES6-module.

Hi, thanks for the response!

I would like just to simplify defining functions anywhere in app e.g. in global scope without annoying function keyword and that's it. Arrow functions are not an option since it has awkward defintion

= () =>

instead of just simple function name, also they have limitations you already mentioned. Even C# has better function defintion e.g.

void myFunctionName() { ... }

but javascript can go futher and make it more concise

myFunctionName() { ... }.

The above works out great because we are already inside a specialized expression when we are in an initializer list, so there is no ambiguity about whether method() calls a function or begins the declaration of one. At this point in the expression, there is no way to call a function without a key: value pair, so it must be the beginning of a declaration.

With your proposed idea, the only way to avoid ambiguity would be to assign a meaning to the presently errorful behavior of putting brackets after parentheses on the same line. A syntax error is currently being thrown in this case because expressions need to be deliminated either by line-breaks or by semicolons, so the brackets after the parentheses are considered part of the expression. Thus, the brackets can only be interpreted as an object initializer, which yields a syntax error due to the parentheses. Another flaw is that statements in JavaScript are generally line-ending-agnostic such that break-points in the statement can contain line-endings without affecting the functionality of the statement. Your proposed idea would only work when the whole thing is on a single line, as putting a new-line between the parentheses and the bracket would conflict with pre-established JavaScript syntax. Therefore, your proposed syntax would conflict with the present harmony of JavaScript syntax and require a redesign/overhaul of some JavaScript parsers. Again, I like your idea. However, in its present state, it does not seem very reasonable/rational.

To resolve the ambiguity, statements starting with function or { are never interpreted as expressions. If you want an expression statement to start with either one of these tokens, you must wrap it in parentheses:

While implicit declarations are more convenient, they seem to introduce some ambiguity when an undeclared symbol is seen. One must have a careful procedure to handle this. If the language is interpreted like python or javascript, this is not really an issue. But for compiled language, surely we must design it so that it is not ambiguous.

In languages that allow "forward references" (i.e. usage of a function whose declaration is only mentioned later in the source code), the typical approach is not to treat them as implicitly declared at the point of usage, but to parse the entire file looking for declarations first, and only then (once there is a complete list of declarations available) analyse usages.

The most vexing parse is a counterintuitive form of syntactic ambiguity resolution in the C++ programming language. In certain situations, the C++ grammar cannot distinguish between the creation of an object parameter and specification of a function's type. In those situations, the compiler is required to interpret the line as a function type specification.

Line 2 above is ambiguous. One possible interpretation is to declare a variable i with initial value produced by converting my_dbl to an int. However, C allows superfluous parentheses around function parameter declarations; in this case, the declaration of i is instead a function declaration equivalent to the following:

It is not possible to disambiguate at present. Although for compatibility reasons you can add such an operator function without using an extension, you should think of it like any other occasion on which you extend a type you don't own by means of an extension. Even when no ambiguity arises because of shadowing, the behavior can get confusing if there's more than one implementation, and there isn't really any way to refer to an implementation in one extension and not another.

It is also possible, instead of specifying an associativity for agiven precedence, to make it a cut operator by using the keyword@cut. A cut operator will override other interpretations even thoughno conflict was detected yet. An example of where this is appropriateis the way JavaScript's function keyword has a different meaning instatement position. A statement can start with an expression, and anexpression can be a function expression, but when we see thefunction token at the start of a statement, we only want to enterthe function declaration statement rule, not the function expressionrule.

There is another possible solution came to my mind: We must put default arg values or vararg args at the end because otherwise it will lead to syntax ambiguity, and no more problems. So can we change the function definition syntax a little so that this kind of ambiguity is avoided?

But functions are only defined as function name(param-list) { body } and called as name(args); With programming languages differing on what to put in the signature/declaration line (what is that called?)

does work in C. That's a function that returns an integer. It also works in sh if the body is not empty. More complicated languages usually don't support this, probably only because of ambiguity. It's too similar to something like:

As more features are made into programming languages, there could be more variations of functions, say generators, virtual, inline, ... I don't think anyone would want to go back and think of removing every tag. They only simplify a tag to an operator because it is used too frequently. But if someone really wants so, I'd argue something that is consist of a name, a list and a body isn't intuitively only possibly a function. Languages with the simplified syntax may have excluded the other possibilities in the design. Many languages have high order functions, but some simple languages may choose to never support them. And using = in place of something like => may mix the definition with array element assignment, but that's not a problem in functional programming languages. And I think ambiguity is the only valid reason.

Ambiguous statements are error-generating statements and the programs containing ambiguity will not compile. Automatic type conversions are the main cause of ambiguity. In C++, the type of argument that is used to call the function is converted into the type of parameters defined by the function. be457b7860