wap-notes

JavaScript loops and string concatenation:

1. for Loop

• The for loop is used when the number of iterations is known beforehand.
• Syntax:

  for (initialization; condition; increment/decrement) {
      // code to be executed
  }
  

• Example:

  for (let i = 0; i < 5; i++) {
      console.log("Iteration: " + i);
  }
  

• Explanation:
  The loop starts with initialization, checks the condition, and executes the block if the condition is true. Then it performs the increment/decrement operation and repeats the process.

2. for/in Loop

• The for/in loop is used to iterate over the properties (keys) of an object.
• Syntax:

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

• Example:

  const person = {name: "Alice", age: 25, city: "New York"};
  for (let key in person) {
      console.log(key + ": " + person[key]);
  }
  

• Explanation:
  This loop iterates over each property in the person object and prints the key-value pairs.

3. for/of Loop

• The for/of loop is used to iterate over iterable objects like arrays, strings, or other collection types.
• Syntax:

  for (variable of iterable) {
      // code to be executed
  }
  

• Example:

  const fruits = ["apple", "banana", "cherry"];
  for (let fruit of fruits) {
      console.log(fruit);
  }
  

• Explanation:
  This loop iterates over each element in the fruits array and prints the element.

4. while Loop

• The while loop is used when the number of iterations is not known, and the loop continues as long as the condition is true.
• Syntax:

  while (condition) {
      // code to be executed
  }
  

• Example:

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

• Explanation:
  The loop checks the condition before executing the block. If the condition is true, the code is executed, and the process is repeated until the condition becomes false.

5. do/while Loop

• The do/while loop is similar to the while loop, but it guarantees that the code block is executed at least once.
• Syntax:

  do {
      // code to be executed
  } while (condition);
  

• Example:

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

• Explanation:
  The code block is executed first, and then the condition is checked. If the condition is true, the loop continues.

6. String and Variable Concatenation

• Using console.log:
  • You can concatenate strings and variables using the + operator.
  • Example:

    let name = "Alice";
    console.log("Hello, " + name + "!");
    

• Using Template Literals (Backticks):
  • Template literals allow embedding variables and expressions within strings using ${} inside backticks (`).
  • Example:

    let name = "Alice";
    console.log(`Hello, ${name}!`);
    

• Explanation:
  Template literals provide a more readable way to concatenate strings and variables, especially when dealing with multiple variables or expressions.

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