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Immediately invoked function expressions can be used to avoid variable hoisting from within blocks, protecting against polluting the global environment and simultaneously allowing public access to methods while retaining privacy for variables defined within the function. In other words, it wraps functions and variables, keeping them out of the ...
The usual alternative is to use named functions and named recursion. Given an anonymous function, this can be done either by binding a name to the function, as in named function expressions in JavaScript, or by assigning the function to a variable and then calling the variable, as in function statements in JavaScript.
A functor is an object of a class type that implements the function-call operator, allowing the object to be used within expressions using the same syntax as a function call. Functors are more powerful than simple function pointers, being able to contain their own data values, and allowing the programmer to emulate closures .
In computer programming, a nested function (or nested procedure or subroutine) is a named function that is defined within another, enclosing, block and is lexically scoped within the enclosing block – meaning it is only callable by name within the body of the enclosing block and can use identifiers declared in outer blocks, including outer ...
The term closure is often used as a synonym for anonymous function, though strictly, an anonymous function is a function literal without a name, while a closure is an instance of a function, a value, whose non-local variables have been bound either to values or to storage locations (depending on the language; see the lexical environment section below).
Notably, the delivery need not be made by the clerk who took the order. A callback need not be called by the function that accepted the callback as a parameter. Also, the delivery need not be made directly to the customer. A callback need not be to the calling function. In fact, a function would generally not pass itself as a callback.
In JavaScript, function objects have an apply method, the first argument is the value of the this keyword inside the function; the second is the list of arguments: func . apply ( null , args ); ES6 adds the spread operator func(...args) [ 3 ] which may be used instead of apply .
Call a function; Provide actual parameters that correspond to a called function's formal parameters; Return control to the caller at the point of call; Consume the return value in the caller; Dispose of the values returned by a call; Provide a private naming scope for variables; Identify variables outside the function that are accessible within it