How can I set a condition to compare variable values in an if statement?

Question

I want to make a condition where the var UPS >= CURRENT along with the other conditions I set. i find the problems is when i compare a variable with another variable.

var BASE = document.getElementById("Base").value;
var UPS = document.getElementById("Ups").value;
var CURRENT = document.getElementById("Current").value;     
var calc = ((UPS-CURRENT)*10);
var result = parseInt(BASE)+parseInt(calc);


if(!isNaN(result) && BASE>0 && UPS>0 && CURRENT>=0 && UPS>=CURRENT)
{       
    document.getElementById("answer").innerHTML="Calculated Potential: "+result;
}
else
{
    document.getElementById("answer").innerHTML="Input valid numbers";
}

I want it so the calculations won't show if there is negative value and if the CURRENT value is more than the UPS value

`UPS` and `CURRENT` are strings. Convert them to numbers before comparing them. — Heretic Monkey, Sep 06 '19 at 21:09
^ This can be easily done with `var BASE = +document.getElementById("Base").value;` - the unary `+` converts to a number for you. — Niet the Dark Absol, Sep 06 '19 at 21:10
Possible duplicate of [Convert a string to an integer?](https://stackoverflow.com/questions/1133770/convert-a-string-to-an-integer) — jhpratt, Sep 06 '19 at 21:13

Jackkobec · Answer 1 · 2019-09-06T21:17:50.620

0

You work with variables of string type. You should convert they to number before use in if statement. The simplest solution is:

if(!isNaN(result) && +BASE > 0 && +UPS > 0 && (+CURRENT >= 0 && +UPS >= +CURRENT)){       
    document.getElementById("answer").innerHTML="Calculated Potential: " +result;
} else {
    document.getElementById("answer").innerHTML="Input valid numbers";
}

edited Sep 06 '19 at 21:17

answered Sep 06 '19 at 21:11

Jackkobec

5,889
34
34

score 0 · Accepted Answer · answered Sep 06 '19 at 21:15

0

Another very easy option:

const validInput = !isNaN(result) && +BASE > 0 && +UPS > 0 && (+CURRENT >= 0 && +UPS >= +CURRENT)
document.getElementById('answer').innerHTML = validInput ? `Calculated Potential: ${result}` : 'Input Valid Numbers'

answered Sep 06 '19 at 21:15

Eunanibus

112
9

Please explain what was changed and why. – jhpratt Sep 06 '19 at 21:15
The + unary converts your strings to integers. The rest of your evaluation is stored. The rest is an Elvis operator. What would you like explained? – Eunanibus Sep 06 '19 at 21:20

How can I set a condition to compare variable values in an if statement?

2 Answers2