Limit decimal number precision

[Gian01]

Hello, I would like to limit a decimal number, with a number of decimal digits preset by me (2 would be fine), there is a funcion to do this?  

[Gondwana · Accepted solution]

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toFixed

[Gian01]

keep giving me Nan as the value of the label... How could I fix it?

[Gian01]

var bar = new Barometer();
bar.onreading = () => {
txtpressure.text = Math.round(bar.pressure / 100);
}
bar.start();

appoggio = (txtpressure/1013).toFixed(2);
console.log(appoggio);

It's appoggio that has a problem...

[Gondwana]

I'm guessing that txtpressure isn't a number, but is a <text> object.

[Gian01]

thank you very much @Gondwana, sorry fot the disturb.

[carlosridg]

It seems like Math.round() is a better solution, but it is not! In some cases it will NOT round correctly. Also, toFixed() will NOT round correctly in some cases.

To correct the rounding problem with the previous Math.round() and toFixed(), you can define a custom JavaScript round function that performs a "nearly equal" test to determine whether a fractional value is sufficiently close to a midpoint value to be subject to midpoint rounding. The following function return the value of the given number rounded to the nearest integer accurately.

Number.prototype.roundTo = function(decimal) {
return +(Math.round(this + "e+" + decimal) + "e-" + decimal);
}

var num = 9.7654;
console.log( num.roundTo(2)); //output 9.77