varfoo = function foo() {return5; } What is a named/anonymous function expression? What is a declared function? How do browsers deal with these constructs differently? They're actually really similar. How you c
The last statement of the function is generally areturnstatement, which starts with a keywordreturn. The value or expression follows it, which is an expectation from the function to return. How to Call functions in JavaScript? Defining a function does notexecuteit. Describing it names the functi...
A function is defined with a "function" statement and named as "square". The function is called to execute as an operand in an expression in its name. One input value is passed into the function at the calling time. The result is returned using the "return" statement. ...
The expression arguments.length returns the number of parameters passed when the function was called. Don't worry if the syntax is unfamiliar, we'll examine it in detail in the next chapter. We'll also see that arguments is technically not an array, but an array-like object....
JavaScript's double not operatoris basically double use of (!) operator. This is alogical not operator. (!!) operator converts non-Boolean to Boolean. As you know,!operator reverses the logic, i.e., it returnfalsefor!truevalue andtruefor!false. ...
Consider the part within the first pair of parentheses: (function(){})();...it is a regular function expression. Then look at the last pair (function(){})();, this is normally added to an expression to call a function; in this case, our prior...
AnArrow FunctioninJavaScriptis a syntactically compact option/ alternative to a regular function expression. These are anonymous functions with their unique syntax that accept a fixed number of arguments and operate in the context of their enclosing scope - i.e., the function or other code where ...
What is the !! Operator? The double negation(!! ) operator is the! Operator twice and calculates the truth value of a value. It returns a Boolean value, which depends on the truthiness of the expression. How It Works: The first ! negates the value, converting it to true or false....
A reliable way for ECMAScript code to test if a valueXis aNaNis an expression of the formX !== X. The result will betrueif and only ifXis aNaN. —18.2.3 isNaN It’s important to note here that this situation is not the same as we have with objects in JavaScript: ...
Functions in JavaScript have access to two inbuilt methods:applyandcall. func.apply(thisArg,argArray)func.call(thisArg,arg1,arg2,...) They allow us invoke a function and explicitly tie it to an object. Any object supplied to thethisArgparameter becomes the function context and what is referenc...