Sum of Two Numbers with Prompt

How to use numbers taken from prompt() and use in calculation?

The prompt() method only returns a string.

You have to convert the string to a number using these methods:

• Number()
• parseInt()
• parseFloat()

Generally you can use Number() method.

Add a sum variable and store the sum result of the numbers to it. The code is given below:

var numOne = prompt('Give me a number'); 
var numTwo = prompt('Give me another number'); 
var sum = Number(numOne) + Number(numTwo);
alert('The sum of your numbers is ' + sum);

How to write a javaScript function to enter 2 numbers through prompts and display the sum of those numbers in an alert?

To do it with only one prompt:

var numbers = prompt("Enter two numbers separated by a semi-colon: ", "");
var a = numbers.split(";")[0];
var b = numbers.split(";")[1];

function calc(a,b)
{
   return parseFloat(a) + parseFloat(b);
}
alert ("The addition of " + numbers + " is = " + calc(a,b));

adding from the window object prompt

So the issue I guess you are facing is that when you add the inputs (eg: 3, 2) you get 32 instead of 5. This happens because the input retrieved by prompt() is a string and it needs to be converted/typecast into a number. You can do this by the Number(input) or parseInt(input, "10") functions.

alert(total = " You entered " + userInput1 + " + " + userInput2 + " which equals " + (Number(userInput1) + Number(userInput2)));

Sum of two numbers and the numbers between them

// prompt user to enter two numbersvar number1 = prompt("Enter first number: ");var number2 = prompt("Enter a number bigger than first number: ");
// convert user input into numbersvar number1 = Number(number1);var number2 = Number(number2);
var start_point= number1;var sum=0;
// display number1document.write(start_point);sum += start_point;start_point++;
while (start_point <=number2) {    document.write(" + " + start_point);    sum += start_point;    start_point++;}

// display sumdocument.write(" = " + sum);

function add() numbers with prompt

Your code is more complicated than it need be. There is no need for a nested function to do the math. You must also convert the user-supplied data to a number (this can be done by prepending a + to the data).

Also, your code does not follow best-practices and standards.

See the comments in the code below.

// Get references to the HTML elements you'll use in JavaScriptvar btn = document.getElementById("btn");var output = document.getElementById("demo");var counter = 0; // Running total will be here
// Set up event handling in JavaScript, not HTMLbtn.addEventListener("click", function() {  counter += +prompt("What is the number to add?"); // Convert response to number and add to counter  output.textContent = counter; // Place result back into the document (use .textContent, not .innerHTML)});

<button id="btn">+</button><p id="demo">0</p>

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