That's correct! The let and const keywords, introduced in ECMAScript 6 (ES6), do not hoist the variable declarations to the top of their scope like var does. Instead, they have block-level scope, meaning they are only accessible within the block they are defined in.

For example:

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console.log(x); // ReferenceError: Cannot access 'x' before initialization
let x = 5;
console.log(x); // 5

In this example, using let instead of var, we get a ReferenceError because the variable x is not hoisted. It is only accessible after the declaration statement. This behavior helps avoid potential bugs and makes code easier to understand when using block-scoped variables.

Similarly, const variables also do not hoist and have block-level scope. The difference is that const variables cannot be reassigned once they are initialized.

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console.log(x); // ReferenceError: Cannot access 'x' before initialization
const x = 5;
console.log(x); // 5

x = 10; // TypeError: Assignment to constant variable

In this case, the const variable x cannot be reassigned a new value after it is declared and initialized. This makes const useful for creating variables that should not be changed.

So, to summarize, var hoists the variable declaration to the top, let and const do not hoist and have block-level scope.

Sure thing! Here are a few more examples of how to use the for loop in JavaScript:

Example 1: Loop through an array

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const numbers = [1, 2, 3, 4, 5];

for (let i = 0; i < numbers.length; i++) {
  console.log(numbers[i]);
}

In this code block, we use a for loop to iterate over an array of numbers. With each iteration of the loop, we access the value of numbers[i] and output it to the console. This loop will output the values 1, 2, 3, 4, and 5.

Example 2: Counting down from a specific number

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for (let i = 10; i >= 0; i--) {
  console.log(i);
}

In this code block, we use a for loop to count down from the number 10 to 0. We start by initializing the loop variable i to 10, and then we set the condition so that the loop will keep running as long as i is greater than or equal to 0. We use the iteration i-- to decrease the value of i by 1 with each loop iteration. This loop will output the values 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, and 0.

Example 3: Looping through an object

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const person = {
  name: 'Jane',
  age: 30,
  email: 'jane@example.com'
};

for (let key in person) {
  console.log(`${key}: ${person[key]}`);
}

In this code block, we use the for...in statement to loop through the properties of an object. With each iteration of the loop, we output the key/value pairs to the console using template literals. This loop will output the values name: Jane, age: 30, and email: jane@example.com.

In JavaScript, the for...in statement is used to iterate over the properties of an object. It loops through the enumerable (i.e., those that can be listed) properties of an object, in an arbitrary order.

The syntax for for...in statement is as follows:

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for (variable in object) {
  // code to be executed
}

Here, variable is a variable used to hold the property name of the object during each iteration, and object is the object whose enumerable properties will be iterated over.

Here is an example of for...in statement that iterates over the properties of an object:

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const student = {
  name: 'Mary',
  age: 22,
  gender: 'female',
  major: 'Computer Science'
};

for (let prop in student) {
  console.log(prop + ": " + student[prop]);
}

In this example, the for...in loop iterates over the properties of student object, and the block of code is executed for each property. For each iteration, the prop variable is assigned to the name of the property, and we use it to access the value of the property.

The output of the above code would be:

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name: Mary
age: 22
gender: female
major: Computer Science