If you’re a web developer, chances are you’re always on the lookout for ways to improve your workflow and get things done faster. Javascript is a versatile language that can be used for front-end, back-end, and even full-stack development.
In this article, we’ve compiled a list of the 10 most useful Javascript tips for web developers, including both beginners and experienced developers. From tips on code organization to performance optimization, these tips will help you take your web development skills to the next level.
1. Use strict mode
In JavaScript, “strict mode” is a way to opt-in to a restricted variant of JavaScript. Strict mode makes it easier to write “secure” JavaScript by eliminating some of the “silent errors” that are possible in regular JavaScript.
To use strict mode, you just need to include the string “use strict” at the top of your JavaScript file or at the top of a function. For example:
"use strict";
function myFunction() {
// code here is executed in strict mode
}Alternatively, you can put the string “use strict” at the top of a function to enable strict mode only for that function:
function myFunction() {
"use strict";
// code here is executed in strict mode
}Here are some of the main changes that strict mode makes to JavaScript:
- Strict mode eliminates some JavaScript silent errors by changing them to throw errors. For example, in strict mode, assigning a value to a read-only property will throw an error, whereas, in regular JavaScript, it would just fail silently.
- Strict mode prohibits the use of certain syntax that is confusing or problematic. For example, in strict mode, you can’t use a variable named “eval” or “arguments”, and you can’t delete variables or functions.
- Strict mode makes it easier to write “secure” JavaScript by disabling features that can be used to inadvertently create insecure code. For example, in strict mode, you can’t use the same name for a function parameter and a variable in the same function.
It’s worth noting that strict mode is only a restricted variant of JavaScript, and it doesn’t add any new features to the language. However, many developers find that strict mode helps them write more reliable and secure code, so it’s often used in production applications.
2. Declare variables with ‘let’ and ‘const’
In JavaScript, `let` and `const` are two ways to declare variables. Both are used to declare variables that can be reassigned, but there are some key differences between the two.
`let` is used to declare variables that can be reassigned. This means that the variable can be initialized more than once and can be changed later on. It is also block-scoped. This means that variables declared with `let` are only available within the block they were declared in. For example, if a `let` variable is declared within a for loop, it will only be available within that for a loop.
let x = 10;
console.log(x); // output: 10
x = 20;
console.log(x); // output: 20`const` is used to declare variables that cannot be reassigned. This means that the variable can only be initialized once and cannot be changed later on. Like `let`, `const` is block scoped and is not hoisted.
const y = 10;
console.log(y); // output: 10
y = 20; // this will throw an errorIt’s worth noting that while the value of a const variable can’t be reassigned, the value itself may still be mutable. For example, if you assign an object to a const variable, you can still modify the properties of that object:
const z = { name: 'John' };
console.log(z); // output: { name: 'John' }
z.name = 'Jane';
console.log(z); // output: { name: 'Jane' }However, if you try to reassign the entire object to a new value, you’ll get an error:
const z = { name: 'John' };
console.log(z); // output: { name: 'John' }
z = { name: 'Jane' }; // this will throw an errorWhy you should avoid using the ‘var’ keyword
Variable declarations using the `var` keyword are subject to `hoisting`. This can lead to unexpected results, particularly in cases where a `var` declaration is used within a loop or an `if` statement. `let` and `const` declarations are both block-scoped. This means that they can only be declared within the block in which they are used. This can help to spot bugs and makes your code more robust.
So which one should you use ‘let’ or ‘const’?
In general, it’s a good practice to use const for variables that don’t need to be reassigned, and use let for variables that do. This can help make your code more readable and easier to understand, as it clearly communicates the intended behavior of the variables.
For example, if you have a variable that stores a value that won’t change throughout the lifetime of your program, you should use const to declare that variable. For example:
const PI = 3.14;On the other hand, if you have a variable that needs to be reassigned at some point, you should use let to declare that variable. For example:
let counter = 0;
counter += 1;
console.log(counter); // output: 1
counter += 1;
console.log(counter); // output: 2It’s worth noting that there may be cases where you want to use let even for variables that don’t need to be reassigned. For example, if you’re using a for loop to iterate over an array, you’ll typically use a let variable to store the loop index:
const names = ['John', 'Jane', 'Mike'];
for (let i = 0; i < names.length; i++) {
console.log(names[i]);
}In this case, the value of i does change with each iteration of the loop, but it’s not intended to be used outside of the loop. In cases like this, using let is fine, as it clearly communicates that the variable is only meant to be used within a specific block of code.
Use template literals
Template strings, available in ES6, offer a convenient way to insert variables and expressions into strings. This eliminates the need for concatenation, making it possible to create complex strings with dynamic elements.
The `template string` syntax is denoted by the backtick (`) character, and they can contain placeholders for expressions, which are represented by ${expression}.characters. They can be used for multi-line strings, string interpolation with embedded expressions, and special constructs called tagged templates.
For example, we can write:
`I'm a template string!`Interpolating
Interpolating variables and expressions is a process of substituting values into a string or expression, this is often referred to as string interpolation. In JavaScript template literals, we insert a variable or expression by adding a dollar sign $ and curly braces {} into the string. This is a much more efficient method than the alternative in old JavaScript, where we would have to concatenate strings like the following:
// Concatenation using template literals
const name = 'Alex';
const age = 25;
const greeting = `Hello, my name is ${name} and I am ${age} years old.`;
console.log(greeting); // "Hello, my name is Alex and I am 25 years old."// Old method of concatenation
const name = 'Alex';
const age = 25;
const greeting = 'Hello, my name is ' + name + ' and I am ' + age + ' years old.';
console.log(greeting); // "Hello, my name is Alex and I am 25 years old."As we can see, the old concatenation syntax can easily lead to syntax errors when working with complex variables and expressions. Template strings are a great improvement in this area.
Multi-Line
Template literals can also contain multi-line strings and string interpolation. Here is an example:
const multiline = `This is a
multi-line string
that contains string interpolation: ${name}`;
console.log(multiline);This will output the following string:
This is a multi-line string that contains string interpolation: Alex
4. Destructuring assignment
The destructuring assignment syntax is a useful JavaScript expression that makes it possible to unpack values from arrays, or properties from objects, into distinct variables. This can be a very convenient way to extract data from structures that are nested or otherwise complex and can make code much more readable.
For example, if the object has properties named name and age, you can assign the object’s value for the name to the first variable and it’s for age to the second.
// Expressions
let name, age;
[name, age] = ['Alex', 25];
console.log(name); // expected output: Alex
console.log(age); // expected output: 25Array destructuring
Destructuring arrays in JavaScript gives you a great way to extract data from arrays into individual variables. This can be especially helpful when working with APIs that return large amounts of data. By destructuring the array, you can access the data more easily and work with it more efficiently.
// Array destructuring
const x = [1, 2, 3];
const [one, two, three] = x;
console.log(one); // 1
console.log(two); // 2
console.log(three); // 3Object destructuring
Javascript object destructuring is a powerful tool that can be used to simplify working with objects. It allows you to extract data from an object and assign it to variables. This can be very useful when working with data structures such as JSON objects.
// Object destructuring
const user = {
name: 'Alex',
age: 25,
};
const { name, age } = user;
console.log(name); // 'Alex'
console.log(age); // 255. Arrow functions
Another impressive feature of Javascript is the arrow function. An arrow function is a shorter syntax for writing a function expression. Arrow functions are anonymous and do not have their own `this` value. They are best suited for non-method functions, and they cannot be used as constructors.
Arrow functions are a great way to create readable and maintainable code compared to regular functions. They were introduced in the ES6 version of JavaScript. Arrow functions get executed after all the function’s parameters have been processed, making them great for working with data.
// Regular function
let add = function(x, y) {
return x + y;
}
// Arrow functions
let add = (x, y) => x + y;Here are some additional features of arrow functions:
- If an arrow function has a single argument, you can omit the parentheses around the argument list. For example, (x) => x * x can be written as x => x * x.
- If an arrow function has a single statement in its body, you can omit the curly braces and the return keyword. The value of the statement is returned implicitly. For example, x => x * x is equivalent to x => { return x * x; }.
- If an arrow function has no arguments, you must include an empty pair of parentheses. For example:
() => console.log('Hello!').Conclusion
Whether you’re a beginner or an advanced Javascript developer, these tips are sure to help you improve your workflow and become a better developer. Try implementing some of these techniques in your projects, and you’ll see how much time they save.
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