Name
Number.toPrecision( ) — format the significant digits of a number
Availability
JavaScript 1.5; JScript 5.5, ECMAScript v3
Synopsis
number
.toPrecision(precision
)
Arguments
-
precision
The number of significant digits to appear in the returned string. This may be a value between 1 and 21, inclusive. Implementations are allowed to optionally support larger and smaller values of
precision
. If this argument is omitted, thetoString( )
method is used instead to convert the number to a base-10 value.
Returns
A string representation of number
that
contains precision
significant digits. If
precision
is large enough to include all
the digits of the integer part of number
,
the returned string uses fixed-point notation. Otherwise, exponential
notation is used with one digit before the decimal place and
precision
-1 digits after the decimal
place. The number is rounded or padded with zeros as necessary.
Throws
-
RangeError
If
digits
is too small or too large. Values between 1 and 21, inclusive, will not cause a RangeError. Implementations are allowed to support larger and smaller values as well.-
TypeError
If this method is invoked on an object that is not a Number.
Example
var n = 12345.6789; n.toPrecision(1); // Returns 1e+4 n.toPrecision(3); // Returns 1.23e+4 n.toPrecision(5); // Returns 12346: note rounding n.toPrecision(10); // Returns 12345.67890: note added zero
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