Number issue with single and double digit

Question

I'm having an issue with some numbers. Currently, I have an input box that displays the result of an equation. If the numbers are between "-25" and "-55", they display green. If the numbers are from "-55" to "-65", they are orange. Anything else outside of those ranges are red. The problem that I am having is that numbers "-3", "-4" and "-5" are all outside of that range, but they display as green. "-6" displays as orange. Those numbers should be red. Am I missing something from my code that would fix that?

Thank you!

var tb = (num1 * num2) + num3 + num4 + num5 + num6 + num7 + num8 + num9 + num10 + num11 + num13 + num12 + num14;

    if (tb > 0) {
        document.calcForm.resist.value = "+" + Math.floor(tb* 100)/100 + " dBm";
    }
    else
    {
        document.calcForm.resist.value = Math.floor(tb* 100)/100 + " dBm";
    }

       document.calcForm.resist.style.color = "green";

   if (document.calcForm.resist.value < "-26" || document.calcForm.resist.value > "-65") {
        document.calcForm.resist.style.color = "red";
   }
   else { if (document.calcForm.resist.value > "-55") {
        document.calcForm.resist.style.color = "orange";
   }}

num1 - num14 are different fields for the equation.

Answer 1

You were comparing strings to strings, which compares alphabetically, not by value. So, you need to convert document.calcForm.resist.value to a number – parseInt(resist.value) (see code):

var tb = (num1 * num2) + num3 + num4 + num5 + num6 + num7 + num8 + num9 + num10 + num11 + num13 + num12 + num14;
var resist = document.calcForm.resist;
if (tb > 0) {
    resist.value = "+" + Math.floor(tb* 100)/100 + " dBm";
}
else
{
    resist.value = Math.floor(tb* 100)/100 + " dBm";
}
resist.style.color = "green";
if (parseInt(resist.value) < -26 || 
    parseInt(resist.value) > -65) {
    resist.style.color = "red";
}
else if (parseInt(resist.value) > -55) {
    resist.style.color = "orange";
}

Answer 2

You are trying to compare values with string type variables. You should not be using quotes for numeric data type.While using numeric comparisons you should use parseInt:

if (parseInt(document.calcForm.resist.value) < -26 || parseInt(document.calcForm.resist.value) > -65) {
        document.calcForm.resist.style.color = "red";
   }

Answer 3

That happens due to the fact that document.calcForm.resist.value is being treated as string/text because you add "+" and + " dBm" to it

document.calcForm.resist.value = "+" + Math.floor(tb* 100)/100 + " dBm";

That's why "-3" > "-26", and "-3" < "-65".

Likewise for the rest.

Think of string comparison as: "-1" > "-10" > "-11"

whereas numerical: -1 < -10 < -11

In addition, you should remove the quotes from the numbers at:

if (document.calcForm.resist.value < "-26" || document.calcForm.resist.value > "-65")

to avoid invoking a string a comparison instead.