Float

_NaN

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let _NaN: float;

The special value "Not a Number".

isNaN

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let isNaN: float => bool;

Tests if the given value is _NaN. Note that both _NaN == _NaN and _NaN === _NaN will return false. isNaN is therefore necessary to test for _NaN.

Returns true if the given value is _NaN, false otherwise.

isFinite

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let isFinite: float => bool;

Tests if the given value is finite. Returns true if the given value is a finite number, false otherwise.

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/* returns [false] */
Js.Float.isFinite(infinity);

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/* returns [false] */
Js.Float.isFinite(neg_infinity);

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/* returns [false] */
Js.Float.isFinite(Js.Float._NaN);

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/* returns [true] */
Js.Float.isFinite(1234.);

toExponential

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let toExponential: float => string;

Formats a float using exponential (scientific) notation. Returns a string representing the given value in exponential notation. Raises RangeError if digits is not in the range [0, 20] (inclusive).

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/* prints "7.71234e+1" */
Js.log @@ Js.Float.toExponential(77.1234);

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/* prints "7.7e+1" */
Js.log @@ Js.Float.toExponential(77.);

toExponentialWithPrecision

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let toExponentialWithPrecision: (float, ~digits: int) => string;

Formats a float using exponential (scientific) notation. digits specifies how many digits should appear after the decimal point. The value must be in the range [0, 20] (inclusive).

Returns a string representing the given value in exponential notation.

The output will be rounded or padded with zeroes if necessary. Raises RangeError if digits is not in the range [0, 20] (inclusive).

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/* prints "7.71e+1" */
Js.log @@ Js.Float.toExponentialWithPrecision(77.1234, ~digits=2);

toFixed

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let toFixed: float => string;

Formats a float using fixed point notation. Returns a string representing the given value in fixed-point notation (usually). Raises RangeError if digits is not in the range [0, 20] (inclusive).

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/* prints "12346" (note the rounding) */
Js.log @@ Js.Float.toFixed(12345.6789);

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/* print "1.2e+21" */
Js.log @@ Js.Float.toFixed(1.2e21);

toFixedWithPrecision

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let toFixedWithPrecision: (float, ~digits: int) => string;

Formats a float using fixed point notation. digits specifies how many digits should appear after the decimal point. The value must be in the range [0, 20] (inclusive). Defaults to 0.

Returns a string representing the given value in fixed-point notation (usually).

The output will be rounded or padded with zeroes if necessary. Raises RangeError if digits is not in the range [0, 20] (inclusive).

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/* prints "12345.7" (note the rounding) */
Js.log @@ Js.Float.toFixedWithPrecision(12345.6789, ~digits=1);

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/* prints "0.00" (note the added zeroes) */
Js.log @@ Js.Float.toFixedWithPrecision(0., ~digits=2);

toPrecision

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let toPrecision: float => string;

Formats a float using some fairly arbitrary rules. Returns a string representing the given value in fixed-point (usually).

toPrecision differs from toFixed in that the former will format the number with full precision, while the latter will not output any digits after the decimal point. Raises RangeError if digits is not in the range accepted by this function.

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/* prints "12345.6789" */
Js.log @@ Js.Float.toPrecision(12345.6789);

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/* print "1.2e+21" */
Js.log @@ Js.Float.toPrecision(1.2e21);

toPrecisionWithPrecision

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let toPrecisionWithPrecision: (float, ~digits: int) => string;

Formats a float using some fairly arbitrary rules. digits specifies how many digits should appear in total. The value must be between 0 and some arbitrary number that's hopefully at least larger than 20 (for Node it's 21. Why? Who knows).

Returns a string representing the given value in fixed-point or scientific notation.

The output will be rounded or padded with zeroes if necessary.

toPrecisionWithPrecision differs from toFixedWithPrecision in that the former will count all digits against the precision, while the latter will count only the digits after the decimal point. toPrecisionWithPrecision will also use scientific notation if the specified precision is less than the number for digits before the decimal point. Raises RangeError if digits is not in the range accepted by this function.

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/* prints "1e+4" */
Js.log @@ Js.Float.toPrecisionWithPrecision(12345.6789, ~digits=1);

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/* prints "0.0" */
Js.log @@ Js.Float.toPrecisionWithPrecision(0., ~digits=2);

toString

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let toString: float => string;

Formats a float as a string. Returns a string representing the given value in fixed-point (usually).

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/* prints "12345.6789" */
Js.log @@ Js.Float.toString(12345.6789);

toStringWithRadix

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let toStringWithRadix: (float, ~radix: int) => string;

Formats a float as a string. radix specifies the radix base to use for the formatted number. The value must be in the range [2, 36] (inclusive).

Returns a string representing the given value in fixed-point (usually). Raises RangeError if radix is not in the range [2, 36] (inclusive).

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/* prints "110" */
Js.log @@ Js.Float.toStringWithRadix(6., ~radix=2);

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/* prints "11.001000111101011100001010001111010111000010100011111" */
Js.log @@ Js.Float.toStringWithRadix(3.14, ~radix=2);

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/* prints "deadbeef" */
Js.log @@ Js.Float.toStringWithRadix(3735928559., ~radix=16);

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/* prints "3f.gez4w97ry0a18ymf6qadcxr" */
Js.log @@ Js.Float.toStringWithRadix(123.456, ~radix=36);

fromString

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let fromString: string => float;

Parses the given string into a float using JavaScript semantics. Returns the number as a float if successfully parsed, _NaN otherwise.

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/* returns 123 */
Js.Float.fromString("123");

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/* returns 12.3 */
Js.Float.fromString("12.3");

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/* returns 0 */
Js.Float.fromString("");

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/* returns 17 */
Js.Float.fromString("0x11");

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/* returns 3 */
Js.Float.fromString("0b11");

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/* returns 9 */
Js.Float.fromString("0o11");

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/* returns [_NaN] */
Js.Float.fromString("foo");

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/* returns [_NaN] */
Js.Float.fromString("100a");