Math.round doesn't work in JavaScript

Question

The code is working fine until I add the line inside the function

parseLocalFloatCnt: num = Math.round(num*1.2);

Does anyone know how to solve this? Thanks

<!DOCTYPE html>
<html>
<body>

<p>Write something in the text field to trigger a function.</p>

<input type="text" id="myInput" oninput="myFunction()">

<p id="demo"></p>

<script>
function myFunction() {
    var x = parseLocalFloatCnt(document.getElementById("myInput").value);
    document.getElementById("demo").innerHTML = "You wrote: " + x;
}
function parseLocalFloatCnt(num) {
    num = Math.round(num*1.2);
    return +(num.replace(getLocalDecimalSeparator(), '.'));
}

function getLocalDecimalSeparator() {
    var n = 1.1;
    return n.toLocaleString().substring(1,2);
}
</script>

</body>
</html>

in your function: `Math.round` return _Number_, you try do `toString` replace separator, and again try get same _Number_, but why??? if you do `return Math.round(num*1.2)` result would be same — Grundy, Sep 09 '15 at 06:56
also see this [post](http://stackoverflow.com/questions/2085275/what-is-the-decimal-separator-symbol-in-javascript) — Grundy, Sep 09 '15 at 06:58

score 3 · Answer 1 · answered Sep 09 '15 at 06:28

3

Uncaught TypeError: num.replace is not a function(…)

You can't call replace on a number.

You could do this instead:

function parseLocalFloatCnt(num) {
    num = Math.round(num*1.2) + ''; // convert `num` to string
    return +(num.replace(getLocalDecimalSeparator(), '.'));
}

answered Sep 09 '15 at 06:28

Cerbrus

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in this case also possibly use `toFixed` instead `Math.round` – Grundy Sep 09 '15 at 06:46
1

@Grundy: That is one of the _many_ possible improvements here ;-) I'm not sure what exactly the OP is trying to do with this code. – Cerbrus Sep 09 '15 at 06:47
yep, also OP pass string in this function, so it can return a `NaN` also, i think :-) – Grundy Sep 09 '15 at 06:49

score 0 · Answer 2 · answered Sep 09 '15 at 06:30

Don't forget num to.String();

<!DOCTYPE html>
<html>
<body>

<p>Write something in the text field to trigger a function.</p>

<input type="text" id="myInput" oninput="myFunction()">

<p id="demo"></p>

<script>
    function myFunction() {
        var x = parseLocalFloatCnt(document.getElementById("myInput").value);
        document.getElementById("demo").innerHTML = "You wrote: " + x;
    }
    function parseLocalFloatCnt(num) {
        num = Math.round(num*1.2).toString();

        return +(num.replace(getLocalDecimalSeparator(), '.'));
    }

    function getLocalDecimalSeparator() {
        var n = 1.1;
        return n.toLocaleString().substring(1,2);
    }
</script>

</body>
</html>

Math.round doesn't work in JavaScript

2 Answers2