1.5 - Converting between numbers and strings
Converting between strings and numbers is particularly useful if we want to use
prompt() to get a number from the user. Without this step
prompt() genreally assumes what it receives is text rather than a number, and just because we ask the user to type a number doesn’t mean they will, so it always pays to double check the content of a variable we have reeived from a user rather than just assuming it to be valid.
We can convert from text strings to numbers, and then back again for printing purposes.
Converting a string to a number
let s = prompt("Type an integer:"); let n = Number(s); // n is a number you can perform calculations on console.log( 2 * n );
Converting a number to a string
let a = 4; let s = a.toString(); console.log("Your number is " + s); console.log( a + a ); console.log( s + s ); // Notice the differnece in output these two sets of additions give
let number_text = prompt("Type an integer:"); let n = Number( number_text ); let answer = n * 2; console.log("Double your number is: "+answer);
Create a program that asks for two numbers, and then prints out:
- The addition of those two numbers
- The subtraction of the first number minus the second
- The multiplication of the two numbers
- The division of the first number divided by the second. Example screen of the expected result: