I need to round the number of a field

I have tried many things about the ro开发者_Go百科unding of a filed but I get NaN, here is what I am trying to round up to 999999,9

document.forms[0].NB_CONCN_MOY_DCO_MS

I have tried Math.round(document.forms[0].NB_CONCN_MOY_DCO_MS.value)

and

document.forms[0].Math.round(NB_CONCN_MOY_DCO_MS.value)

what can I do now.

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If you want to round a number to one decimal place in JavaScript, use someNumber.toFixed(1). Note that the value of form fields is a string (not a number) so you'll want to convert it to a number first.

var n = document.forms[0].NB_CONCN_MOY_DCO_MS.value * 1;
var rounded = n.toFixed(1);

If your value has commas in it to represent decimal values, you will need to fix the string to use periods instead first:

var n = document.forms[0].NB_CONCN_MOY_DCO_MS.value.replace(/,/,',') * 1;
var rounded = n.toFixed(1);