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4. Function() > Functions Are First-Class Citizens (Not Just Syntax but Values)
Functions Are First-Class Citizens (Not Just Syntax but Values)
In JavaScript, functions are objects. This means that a function can be stored in a variable, array, or object. Also, a function can be passed to, and returned from, a function. A function has properties because it is an object. All of these factors make functions first-class citizens in JavaScript.
<!DOCTYPE html><html lang="en"><body><script> /* functions can be stored in variables (funcA), arrays (funcB), and objects (funcC) */ var funcA = function(){}; // called like so: funcA() var funcB = [function(){}]; // called like so: funcB[0]() var funcC = {method: function(){}}; // too.method() or funcC['method']() // functions can be sent to, and sent back from, functions var funcD = function(func){ return func }; var runFuncPassedToFuncD = funcD(function(){console.log('Hi');}); runFuncPassedToFuncD(); // functions are objects, which means they can have properties var funcE = function(){}; funcE.answer = 'yup'; // instance property console.log(funcE.answer); // logs 'yup' </script></body></html>
