In CSS, you can use the @media rule to show or hide elements based on the size of the viewport. To hide an <img> in responsive mode, you can use the display: none rule within an @media rule as follows:

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@media (max-width: 600px) {
  img {
    display: none;
  }
}

The @media rule includes a max-width condition of 600px, which means that any <img> elements will be hidden when the viewport is less than 600px.

You can learn more about the @media rule here: https://www.w3schools.com/css/css_rwd_mediaqueries.asp.

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if(condition) {
   // execute this block if condition is true
} else {
   // execute this block if condition is false
}

An example statement could be the following:

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if(x > 5) {
   System.out.println("x is greater than 5");
} else {
   System.out.println("x is less than or equal to 5");
}

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// Get geolocation data 
navigator.geolocation.getCurrentPosition(function(position) {

  // Set latitude and longitude 
  let lat = position.coords.latitude;
  let lon = position.coords.longitude;

  // Fetch data from the openweathermap API
  fetch(`http://api.openweathermap.org/data/2.5/weather?lat=${lat}&lon=${lon}&APPID=<YOUR_API_KEY>`)
    .then(response => response.json())
    .then(data => {

      // Set a condition for the background image
      let condition = data.weather[0].main;
      let backgroundImage = '';
      // Select images based on condition
      switch(condition.toLowerCase()) {
        case 'clouds': backgroundImage = '/images/cloudy.jpg'; break;
        case 'rain': backgroundImage = '/images/rainy.jpg'; break;
        case 'snow': backgroundImage = '/images/snowy.jpg'; break;
        case 'clear': backgroundImage = '/images/sunny.jpg'; break;
        default: backgroundImage = '/images/default.jpg';
      }

      // Create a style element and set the selected image as the background
      let styleNode = document.createElement("style");
      document.head.appendChild(styleNode);
      styleNode.innerHTML = `html body { background-image: url('${backgroundImage}'); }`;
   });
});

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const promise = new Promise((resolve, reject) => {
    if (someCondition) {
        resolve('the promise was fulfilled');
    }
    reject('the promse was rejected');
});

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if (condition1 && condition2) {
  // execute code
}

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function recursiveFunction(parameter){
  //base condition
  if (condition) { 
    return;
  }
  //recursive case
  else { 
    //modify parameter
    parameter = update(parameter);
    //recursive call
    recursiveFunction(parameter);
  }
}

A guard clause in JavaScript is a statement that is used to check if the remaining lines of code should be executed or not. It helps to prevent unnecessary computation and DRY (Don't Repeat Yourself) up the code.

An example of a guard clause in JavaScript would be as follows:

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if (condition) {
  //Execute code 
}

In this example, the condition specifies when the code should be executed. If the condition is evaluated to be true, then the code is executed. Otherwise, it is skipped.

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let age = prompt("What is your age?");

confirm(age <= 17 ? "Do you study at school?" : "Thanks for your answer.");

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if (condition) {
  // code
} else {
  // code
}

Yes, an if…else statement is a way to execute different code depending on whether a condition is true or false. The basic structure of an if…else statement looks like this in JavaScript:

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if (condition) {
  //Code to run if condition is true
} else {
  //Code to run if condition is false
}

You can learn more about if…else statements here.

In JavaScript, a while loop is a control flow statement that executes a block of code repeatedly, based on a given condition. Here is an example of a while loop in JavaScript:

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var count = 0;

while (count < 10) {
  console.log("Count is: " + count);
  count++;
}

In the example above, the loop will execute and print Count is: 0, followed by Count is: 1, and so on up to, but not including, Count is: 10. In the example, the block of code will execute as long as the count variable is less than 10.

An if...else statement is a type of control statement which allows a program to execute different instructions depending on the condition of a given expression. It is composed of a condition and instructions to execute if the condition is true, and instructions to execute if the condition is false.

In C/C++ or Java, an if...else statement looks like this:

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if (condition) {
  // Instructions to be executed if the condition is true
}
else {
  // Instructions to be executed if the condition is false 
}

For more information about if...else statements, please see this article from TutorialsPoint.

This can be solved using a combination of looping and conditional statements. Below is an example solution in JavaScript.

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function isSpecialNumber(input) {
  let numString = input.toString();  // Convert input to a string

  // Loop through each character in number string
  for (let i = 0; i < numString.length; i++) {
    // Convert current char to int
    let currentNum = parseInt(numString.charAt(i));
    // Check if current number is not in the specified range
     if (currentNum > 5) {
      return false; // Not a special number
    }
  }

  return true; // All chars in the range -> Special Number
}

References:

• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/charAt

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function travel() {
    let name = prompt("What is your name?");
    let email = prompt("What is your email?");
    let travel = prompt("Do you enjoy traveling?");

    if (travel === "yes") {
        alert("Thank you " + name + "! I'll be in touch via email 😁");
    }
    else if (travel !== "yes") 
        alert("Thank you " + name + "! We won't bother you with emails at the moment, but if you change your mind, let us know!");
}

An if/else statement is a control flow statement in many programming languages which allows for code to be executed conditionally. For example, in JavaScript:

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if (x > 0) {
  console.log('x is greater than 0')
} else {
  console.log('x is not greater than 0')
}

For more information, please see the Mozilla documentation.

You can use the Array.prototype.includes() method to compare elements from an array and add conditions accordingly.

For example, using JavaScript:

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let arr = [1, 2, 3, 4, 5];

if (arr.includes(3)) {
  console.log('3 is included')
}

More information about Array.prototype.includes() is available in MDN Web Docs for Array.prototype.includes().