Javascript "less Than" If Statement Failing

Here is my function: function reCalculate(i) { document.getElementById('Q' + i).value = document.getElementById('C' + i).value - document.getElementById('QA' + i).value; i

Solution 1:

When you pull the .value of an element it returns a string. '10'<'2' will return true.

You can simply do a parseInt/parseFloat on the value, ala

var q = parseInt(document.getElementById("Q"+i).value,10)

Solution 2:

Thats because it is considering your Q as a string while comparing.

Try the following instead:

functionreCalculate(i){

    var Z = document.getElementById, P = parseInt; 

    var qElem = Z("Q"+i);
    var q = P(qElem.value, 10);
    var c = P(Z("C"+i).value, 10);
    var qa = P(Z("QA"+i).value, 10);
    var e = P(Z("E"+i).value, 10);

    q = c - qa;

    if (q < 0) qElem.value = 0;

    if (q < e && q != 0){
        alert(q+" is less than "+e+"?");
        qElem.value = e;
    }

    qElem.value = Math.ceil(q);
}

Solution 3:

May be you should do a

parseFloat(document.getElementById("Q"+i).value)

to make sure you are comparing numbers

Solution 4:

You are comparing strings not numbers. Use the unary + to convert to a number:

if (+document.getElementById("Q" + i).value < +document.getElementById("E" + i).value ...)

You should use variables by the way:

var input_one = document.getElementById("Q" + i).value,
    input_two = document.getElementById("E" + i).value;

if (+input_one < +input_two) {

}