How to force JS to do math instead of putting two strings together

the simplest:

dots = dots*1+5;

the dots will be converted to number.

I'm adding this answer because I don't see it here.

One way is to put a '+' character in front of the value

example:

var x = +'11.5' + +'3.5'

x === 15

I have found this to be the simplest way

In this case, the line:

dots = document.getElementById("txt").value;

could be changed to

dots = +(document.getElementById("txt").value);

to force it to a number

NOTE:

+'' === 0
+[] === 0
+[5] === 5
+['5'] === 5

DON'T FORGET - Use parseFloat(); if your dealing with decimals.

You have the line

dots = document.getElementById("txt").value;

in your file, this will set dots to be a string because the contents of txt is not restricted to a number.

to convert it to an int change the line to:

dots = parseInt(document.getElementById("txt").value, 10);

Note: The 10 here specifies decimal (base-10). Without this some browsers may not interpret the string correctly. See MDN: parseInt.

Related