Procedural Programming: Focuses on execution flow and control, implementing functionality through sequential execution of statements. The execution process of these statements is the entire program.
Object-Oriented Programming: Organizes data and instructions into modules, achieving reuse through inheritance, polymorphism, delegation, and other methods.
Functional Programming: Core idea is to write computational processes as a series of nested function calls, focusing on what to do rather than how to do it.
Logic Programming: Only concerns itself with rules, facts, and problem derivation in a standardized way, without needing to worry about program control or specific implementation algorithms.
When searching for JavaScript encapsulation online, you'll often see keywords like object-oriented and functional programming. The core of all these approaches is to wrap abstract detailed logic, optimize and handle details, reduce development complexity, and provide it to users. We don't need to understand the deep encapsulation details to quickly use this logic and achieve our desired applications.
For example, the three major modern JS frameworks are also deeply encapsulated, providing developers with convenient APIs and framework environments~
Assignment expression;
function add(m) {
return function (n) {
return m + n;
};
}
add(10)(20) >> 30;
Complex expression: (x => y => x + y)(10)(20);
We use closure characteristics to temporarily store the values of m and n respectively. After returning, memory will be released, and we can get 30 as the return value.
We can also use complex expression syntax to rewrite the above code. Both writing methods are equivalent.
There are many application scenarios, for example, when we need to use regex to validate user input values and check for unexpected inputs. This encapsulation method can be used in such cases.
We can return the values we want through an encapsulated function, and we can even combine these logics through the nesting patterns shared before, which is quite interesting.
const arr = [1, 3, 'a', 'd', 5, 8, '9'];
// Encapsulation to filter out numbers
function getNumbers(arr) {
const newArr = [];
arr.forEach((item) => {
if (typeof item === 'number') {
newArr.push(item);
}
});
return newArr;
}
getNumbers(arr); // Get numbers
function getEvenNumbers(arr) {
const newArr = [];
arr.forEach((item) => {
if (item % 2 === 0) {
newArr.push(item);
}
});
return newArr;
}
getEvenNumbers(getNumbers(arr)); // Get even numbers
function tellMe(b) {
return b === true ? 'can' : 'cannot';
}
tellMe(false);
function isNumberEven(number) {
return number > 0 ? (number % 2 === 0) : false;
}
isNumberEven(8);
Can also combine with previous applications;
function conditionOne(a, b) {
return console.log(`${a.name} is ${a.height - b.height}cm taller than ${b.name}, he goes to military service`);
}
function conditionTwo(a, b) {
return console.log(`${b.name} is ${b.height - a.height}cm taller than ${a.name}, he goes to military service`);
}
function beSoldier(a, b) {
return a.height > b.height ? conditionOne(a, b) : conditionTwo(a, b);
}
beSoldier({ name: 'Aaron', height: 180 }, { name: 'Eric', height: 170 }); // Aaron goes to military service QQ
This is the method used by frameworks, mounting things to the window for convenient access.
// eslint-disable-next-line no-shadow-restricted-names
(function (root, undefined) {
// Private state
const age = 20;
const name = 'aaron';
let money = 87;
function show(x) {
return x === 'you'
? `Your name is ${name} and ${age} years old.`
: x === 'money'
? `your money is ${money}`
: 'what?';
}
function getMoney() {
return `your money is ${money}`;
}
function setMoney(m) {
return (money += m);
}
function codingTime() {
return (
`${Math.abs(new Date(2022, 11) - new Date(2020, 10)) / (1000 * 60 * 60 * 24)} days`
);
}
// Save reference externally, a simple way to expose methods
root.Who = { show, getMoney, setMoney, codingTime };
})(window);
Who.show('you');
Who.show('age');
Who.codingTime();
With these methods introduced above, if you apply good detail handling and mutual application, you can also write interesting libraries for people to use~
