toPrecision method
Implementation
double toPrecision(int fractionDigits) {
if (fractionDigits < 0) {
throw RangeError('fractionDigits must be non-negative: $fractionDigits');
}
if (isNaN || isInfinite) {
return this;
}
var factor = pow(10, fractionDigits.toDouble()).toDouble();
return ((this * factor).round().toDouble() / factor);
}