Can anyone say whether the following code is possible or not ? If possible then please give expected output and explanation.

Question

a=prompt();
document.write((a+=10)+"<br/>"+(a-=11));

Answer 1

Why use a+=10 if you can simply use a+10 ? += only changes the value of the variable, but does not return anything.

Answer 2

Why don't you try it yourself 🙂🙃👇

https://code.sololearn.com/W1hcwlLp15w7/?ref=app

Answer 3

I have tried it and I have got the output. But I am seeking for the explanation of the output…

Answer 4

Prompt returns a string.
When JavaScript tries to operate on a "wrong" data type, it will try to convert the value to a "right/correct" type.

5 + null // returns 5 because null is converted to 0
"5" + null // returns "5null" because null is converted to "null"
"5" + 2 // returns "52" because 2 is converted to "2"
"5" - 2 // returns 3 because "5" is converted to 5
"5" * "2" // returns 10 because "5" and "2" are converted to 5 and 2
reference from W3Schools.com

https://code.sololearn.com/WcDytXNgw5XL/#js