JavaScript: Check whether a string starts with 'Java' and false otherwise

JavaScript Basic: Exercise-27 with Solution

Write a JavaScript program to check whether a string starts with 'Java' if it does not otherwise.

This JavaScript program checks whether a given string starts with 'Java'. It uses a method to determine if the string begins with the specified substring 'Java'. If the string starts with 'Java', it returns true; otherwise, it returns false. This approach efficiently handles the comparison, providing a clear and concise solution.

Visual Presentation:

Sample Solution:

JavaScript Code:

// Define a function named start_spec_str that takes a parameter str
function start_spec_str(str) {
  // Check if the length of str is less than 4
  if (str.length < 4) {
    // If true, return false
    return false;
  }
  // Extract the first four characters of str
  front = str.substring(0, 4);
  // Check if front is equal to 'Java'
  if (front == 'Java') {
    // If true, return true
    return true;
  } else {
    // If not equal to 'Java', return false
    return false;
  }
}

// Log the result of calling the start_spec_str function with the argument "JavaScript" to the console
console.log(start_spec_str("JavaScript"));

// Log the result of calling the start_spec_str function with the argument "Java" to the console
console.log(start_spec_str("Java"));

// Log the result of calling the start_spec_str function with the argument "Python" to the console
console.log(start_spec_str("Python")); 

Output:

true
true
false

Live Demo:

See the Pen JavaScript: check if a string starts with Java -basic- ex-27 by w3resource (@w3resource) on CodePen.

Flowchart:

ES6 Version:

 // Using ES6 arrow function syntax to define the start_spec_str function
const start_spec_str = (str) => {
  // Check if the length of str is less than 4
  if (str.length < 4) {
    // If true, return false
    return false;
  }
  // Extract the first four characters of str
  const front = str.substring(0, 4);
  // Check if front is equal to 'Java'
  if (front === 'Java') {
    // If true, return true
    return true;
  } else {
    // If not equal to 'Java', return false
    return false;
  }
};

// Log the result of calling the start_spec_str function with the argument "JavaScript" to the console
console.log(start_spec_str("JavaScript"));

// Log the result of calling the start_spec_str function with the argument "Java" to the console
console.log(start_spec_str("Java"));

// Log the result of calling the start_spec_str function with the argument "Python" to the console
console.log(start_spec_str("Python"));

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