ToPrecision( number, precision, round ) - Node.js Math

Node.js examples for Math:Round

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Description

ToPrecision( number, precision, round )

Demo Code

/**/*from   w w  w  . j  a v a2  s.  c  o  m*/
 * toPrecision( number, precision, round )
 *
 * @number (Number)
 *
 * @precision (Number) significant figures precision (not decimal precision).
 *
 * @round (Function)
 *
 * Return number.toPrecision( precision ) using the given round function.
 */
return function( number, precision, round ) {
  var roundOrder, roundIncrement;

  // Get number at two extra significant figure precision.
  number = number.toPrecision( precision + 2 );

  // Then, round it to the required significant figure precision.
  roundOrder = Math.ceil( Math.log( Math.abs( number ) ) / Math.log( 10 ) );
  roundOrder -= precision;
  roundIncrement = Math.pow( 10, roundOrder );

  number = round( number, roundIncrement );

  // Ignore decimal error, eg. `1234 * 0.0001 = 0.12340000000000001`.
  if ( roundOrder < 0 ) {
    number = +number.toFixed( -roundOrder );
  }

  return number;
};

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