JavaScript Programs Mocktest

The output will be "22". In JavaScript, when you use the + operator with strings, it concatenates them. So, 2 + 2 results in 4, and then "4" + "2" results in "42".

The code snippet swaps the values of variables a and b. It uses a temporary variable temp to hold the value of a, then assigns b to a, and finally assigns the value of temp (which was the original value of a) to b. So, after execution, a will have the value of 20 and b will have the value of 10, and the output will be 20 10.

The output will be "object". In JavaScript, typeof null returns "object". This is a historical artifact and doesn't reflect the true nature of null, which is its own primitive type.

The code snippet assigns the value of x to y first (y = x), which is 5. Then, it increments x (x++), so after execution, x will be 6 and y will be 5. The output will be 6 5.

The output will be "Hello12". In JavaScript, the + operator is used for both addition and concatenation. Since the expression starts with a string, JavaScript treats the subsequent numbers as strings and concatenates them.

The code snippet calculates and stores the length of the string "Hello" (which is 5) in the variable y. Therefore, the output will be 5.

The output will be 10. In JavaScript, when you use the - operator with strings that can be converted to numbers, JavaScript performs numeric subtraction. So, "20" - 10 is equivalent to 20 - 10, which results in 10.

The code snippet converts the string x to uppercase using the toUpperCase() method. This method returns a new string with all alphabetic characters converted to uppercase. Therefore, the output of the code will be "HELLO".

The output will be "Even". The code checks if the number x is even or odd by using the % modulus operator to check if x is divisible by 2 without a remainder (x % 2 === 0). Since 8 is divisible by 2 without a remainder, the condition is true, and the code inside the if block executes, logging "Even" to the console.

The code snippet calculates the sum of all numbers in the array numbers using the reduce method. The reduce method takes a callback function as an argument, which receives two parameters (total and num). It starts with an initial value of 0 and adds each number from the array numbers to the total in each iteration. After iterating through all elements, it returns the final sum, which is then logged to the console. In this case, the sum of elements 1 + 2 + 3 + 4 + 5 = 15, which is the output of the code.