You have used null. You have used undefined. But, have you ever thought about what they mean to the world and to Javascript? The fact is quite simple - we can’t do a null equality check. 1 2 3 4 console.log(1 == null); // false console.log(0 == null); // false console.

You can use bind to bind variables of a function, and execute the said function later to get the desired result. You have seen how how closures can be used in Javascript and a bit about currying functions. Here’s one more way of doing that. We can bind available variables for a function and execute function at a later time.

You can easily chain methods along with variables to find a highly readable, and totally sensible scope chain. We have seen how closures can be used in Javascript before. Let us see some more practical usage scenarios. Consider the below closure - 1 2 3 4 5 6 7 8 9 function getProduct(x) { return function(y) { return y * x; }; } const twice = getProduct(2); console.

Functions are objects in Javascript. So, we could use functions as objects within other functions. So, the below is valid - 1 2 3 4 5 6 7 8 9 10 11 12 function getProductPlus(x, y) { function factoredResult() { const factor = 2; //console.log("factored : ", x * y * factor); return x * y * factor; } return factoredResult; } let prod = getProductPlus(3, 5); console.

We have come to love and respect the fact that (almost) everything is an object in Javascript and we can use all kinds of variables without giving a damn about their types. But, we also can understand that Javascript is trying to work its magic when we throw all caution to the wind.

An object’s key can be anything - even a reserved keyword. And, this may cause unexpected problems in some script engines. Consider - 1 2 3 4 5 const operations = { add: "add something", delete: "remove something", prototype: "do something" }; operations is valid. And, you can go ahead and use the props in any way you wish.

You can quite easily sort arrays on multiple attributes using a simple Array.sort(). Consider this array - 1 2 3 4 5 6 const students = [ { name: "Rama", grade: 10, class: 5 }, { name: "Kris", grade: 7, class: 1 }, { name: "Jan", grade: 8, class: 5 }, { name: "Kris", grade: 5, class: 7 } ]; Sorting based on grade is easy.

You can use the ... operator to perform black magic in Javascript. Consider the below example - 1 2 3 4 5 6 const arrNums = [1, 2, 3]; const arrMoreNums = [4, 5, 6]; const allNums = [...arrNums, ...arrMoreNums]; console.log("allNums: ", allNums); // [ 1, 2, 3, 4, 5, 6 ] This is much much more efficient than writing code to go through two loops and merging them.

How can you use methods of one object type against another object type? How can you use the feature to your advantage? In another post, we had discussed how Javascript can use call to invoke methods of a function in a different context. We can use this feature to our advantage.

Check if a given object is empty without considering any custom props defined by prototype. Consider this sample object - 1 const earth = {}; Use Object.entries() or equivalent Object.entries gives us a short way to access entries in an array form. We could just check whether entries are empty to decide whether the parent object is empty.

A function can have its own methods - strange but true. Why? Because everything in Javascript is an object and object can have methods. Consider - 1 2 3 4 5 6 function getSum(x, y) { return x + y; } console.log(getSum(1, 2)); //3 console.log(getSum.call(this, 1, 2)); //3 The first call to getSum is as expected.

Chainable interfaces make your code readable and, arguably, your life more enjoyable. Chainable interfaces are those series of methods that you see chained to an object. You can use them for objects where “relevant”. Commonly used functions It is common to see methods chained to one another. The chaining works from left to right, with results from the left-side of the function passed to the right in sequence.

Do not set properties to null or empty, always use delete. Consider - 1 2 3 const earth = { name: "earth", position: 3, aweIndex: 42 }; console.log(earth); // { name: 'earth', position: 3, aweIndex: 42 } If you set any property to null - 1 2 3 earth["aweIndex"] = undefined; console.