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Different ways of writing javascript

PHPzOriginal: 2023-05-09 14:58:37488browse

JavaScript is a widely used programming language that can be used along with HTML and CSS to build dynamic websites and applications. In JavaScript, there are many different ways of writing to achieve the same goal. Below we’ll explore some different ways to write JavaScript and their pros and cons.

Original JavaScript writing method

This is the earliest JavaScript writing method, which uses document objects to build web pages. In this way of writing, JavaScript code is usually embedded directly in the HTML file. For example:

<!DOCTYPE html>
<html>
<head>
    <title>My Website</title>
    <script type="text/javascript">
        var message = "Hello, World!";
        document.write(message);
    </script>
</head>
<body>
</body>
</html>

This writing method is easy to learn and understand, but it has some shortcomings. First, it makes HTML files cluttered and difficult to manage. Secondly, if you have multiple JavaScript code blocks, you need to define all variables and functions in each code block. Finally, this approach is not safe as it is vulnerable to cross-site scripting attacks.

Declarative JavaScript writing method

Another way of writing JavaScript is declarative JavaScript writing, which uses external script files to store code. To use this writing method, you can include a script element in the HTML file and specify the src attribute. For example:

<!DOCTYPE html>
<html>
<head>
    <title>My Website</title>
    <script src="scripts/my_script.js"></script>
</head>
<body>
</body>
</html>

In the my_script.js file, you can write all JavaScript code. This way of writing is easier to manage and maintain because it allows the code to be separated and organized into different files. Additionally, it allows the same code to be reused across multiple pages. However, this way of writing still requires variables and functions to be defined in the global namespace, which is prone to naming conflicts.

Modular JavaScript writing method

Modular JavaScript writing method is a more advanced writing method that uses JavaScript modules to organize and encapsulate code. A module is a closed unit of variables, functions, and classes that are visible only inside the module. Modules can be defined in files and communicate with other modules through import and export statements. For example:

// 模块 my_module.js

let message = "Hello, World!";

function showMessage() {
    console.log(message);
}

export default showMessage;

// 模块 main.js

import showMessage from "./my_module.js";

showMessage();

This way of writing makes the code more modular and reusable. It improves code security by hiding implementation details and reduces the possibility of naming conflicts. Furthermore, the idea behind modularity is also a core concept in modern web frameworks.

Functional JavaScript writing

Functional JavaScript writing is a paradigm that emphasizes pure functions, that is, those that do not introduce side effects and only calculate return values based on their inputs function. This way of writing emphasizes function composition and piping to make it easier to write high-quality, testable, and understandable code. For example:

const add = x => y => x + y;
const multiply = x => y => x * y;

const calculate = (x, y) => {
    const addResult = add(x)(y);
    const multiplyResult = multiply(x)(y);
    return addResult + multiplyResult;
};

console.log(calculate(2, 3)); // 11

This way of writing can improve the readability and maintainability of the code. It's also easier to unit test since each function is independent.

Conclusion

There are many different ways to write JavaScript to achieve the same goal. Different writing methods have different advantages and disadvantages, and you can choose the appropriate method according to the specific situation. However, modularity and functional programming thinking are core concepts in modern JavaScript development and are worth learning and using in depth.

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