How Do You Determine if a JavaScript Variable Holds a Function?

Determining Function Variable Types with JavaScript

In JavaScript, variables can hold different types of data, including functions. Functions are a special type of object that can be assigned to variables and executed when needed. To check if a variable is of function type, you can use the typeof operator.

The typeof operator returns a string representing the type of the variable it's applied to. For example, for a variable a defined as:

var a = function() {/* Statements */};

Using typeof on a will return the string 'function'. This indicates that a is a function type variable.

To incorporate this check into a function, you can use the following code:

function foo(v) {
  if (typeof v === 'function') {
    // Do something if `v` is a function
  }
}

Calling foo with the a variable as an argument, foo(a), will execute the code within the if statement since a is of function type. You can customize the actions performed within that code block to perform the desired operations when the variable is indeed a function.

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