Here are some basic concepts and features of JavaScript that you should remember

1. Variables

Variables are used to store data values.

let name = "Alice";
const age = 25;
var isStudent = true;

2. Data Types

JavaScript has several data types including:

• String
• Number
• Boolean
• Object
• Array
• Undefined
• Null

3. Operators

Operators are used to perform operations on variables and values.

• Arithmetic: +, -, *, /, %
• Assignment: =, +=, -=, *=, /=
• Comparison: ==, ===, !=, !==, >, <, >=, <=
• Logical: &&, ||, !

4. Functions

Functions are blocks of code designed to perform a particular task.

function greet(name) {
    return "Hello, " + name;
}

5. Conditionals

Conditional statements are used to perform different actions based on different conditions.

if (age > 18) {
    console.log("Adult");
} else {
    console.log("Minor");
}

6. Loops

Loops are used to execute a block of code repeatedly.

• for loop

javascriptコードをコピーするfor (let i = 0; i < 5; i++) {
    console.log(i);
}

• while loop

let i = 0;
while (i < 5) {
    console.log(i);
    i++;
}

7. Arrays

Arrays are used to store multiple values in a single variable.

let fruits = ["Apple", "Banana", "Cherry"];

8. Objects

Objects are collections of properties and methods.

let person = {
    firstName: "John",
    lastName: "Doe",
    age: 30,
    greet: function() {
        console.log("Hello, " + this.firstName);
    }
};

9. DOM Manipulation

JavaScript can interact with the HTML and modify its structure or content.

document.getElementById("myElement").innerHTML = "New Content";

10. Events

JavaScript can respond to user actions like clicks, mouseovers, etc.

document.getElementById("myButton").addEventListener("click", function() {
    alert("Button clicked!");
});

summary

Understanding these basics will give you a strong foundation in JavaScript. As you become more comfortable, you can explore more advanced topics like asynchronous programming, closures, and ES6+ features.