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Number

Generate numeric values.

integer​

Signed integer values.

Generate any possible integer in the specified range. Both the lower bound and upper bound of the range are included in the set of possible values.

Signatures:

  • fc.integer()
  • fc.integer({min?, max?})

with:

  • min? — default: -2147483648 — lower bound of the range (included)
  • max? — default: 2147483647 — upper bound of the range (included)

Usages:

fc.integer();
// Note: All possible integers between `-2147483648` (included) and `2147483647` (included)
// Examples of generated values: -1064811759, -2147483638, 2032841726, 930965475, -1…

fc.integer({ min: -99, max: 99 });
// Note: All possible integers between `-99` (included) and `99` (included)
// Examples of generated values: 33, -94, 5, -2, 97…

fc.integer({ min: 65536 });
// Note: All possible integers between `65536` (included) and `2147483647` (included)
// Examples of generated values: 487771549, 1460850457, 1601368274, 1623935346, 65541…

Resources: API reference.
Available since 0.0.1.

nat​

Positive integer values (including zero).

Generate any possible positive integer between zero and the upper bound. Both zero and the upper bound are included in the set of possible values.

Signatures:

  • fc.nat()
  • fc.nat({max?})
  • fc.nat(max)

with:

  • max? — default: 2147483647 — upper bound of the range (included)

Usages:

fc.nat();
// Note: All possible integers between `0` (included) and `2147483647` (included)
// Examples of generated values: 2, 5, 2147483618, 225111650, 1108701149…

fc.nat(1000);
// Note: All possible integers between `0` (included) and `1000` (included)
// Examples of generated values: 2, 8, 4, 270, 0…

fc.nat({ max: 1000 });
// Note: All possible integers between `0` (included) and `1000` (included)
// Examples of generated values: 917, 60, 599, 696, 7…

Resources: API reference.
Available since 0.0.1.

maxSafeInteger​

All the range of signed integer values.

Generate any possible integer ie. from Number.MIN_SAFE_INTEGER (included) to Number.MAX_SAFE_INTEGER (included).

Signatures:

  • fc.maxSafeInteger()

Usages:

fc.maxSafeInteger();
// Examples of generated values: 4, -6906426479593829, -9007199254740981, 1468597314308129, -31…

Resources: API reference.
Available since 1.11.0.

maxSafeNat​

All the range of positive integer values (including zero).

Generate any possible positive integer ie. from 0 (included) to Number.MAX_SAFE_INTEGER (included).

Signatures:

  • fc.maxSafeNat()

Usages:

fc.maxSafeNat();
// Examples of generated values: 8974418498592146, 7152466311278303, 7682568104547082, 5480146126393191, 6062166945524051…

Resources: API reference.
Available since 1.11.0.

float​

Floating point values with 32-bit precision.

Generate any floating point value taken into the specified range. The lower and upper bounds are included into the range of possible values.

It always generates valid 32-bit floating point values.

Signatures:

  • fc.float()
  • fc.float({min?, max?, minExcluded?, maxExcluded?, noDefaultInfinity?, noNaN?, noInteger?})

with:

  • min? — default: -∞ and -3.4028234663852886e+38 when noDefaultInfinity:true — lower bound for the generated 32-bit floats (included)
  • max? — default: +∞ and +3.4028234663852886e+38 when noDefaultInfinity:true — upper bound for the generated 32-bit floats (included)
  • minExcluded? — default: false — do not include min in the set of possible values
  • maxExcluded? — default: false — do not include max in the set of possible values
  • noDefaultInfinity? — default: false — use finite values for min and max by default
  • noNaN? — default: false — do not generate Number.NaN
  • noInteger? — default: false — do not generate values matching Number.isInteger

Usages:

fc.float();
// Note: All possible 32-bit floating point values (including -∞, +∞ and NaN but also -0)
// Examples of generated values: -1.1428610944376996e+35, -4.923316419364955e-39, 7.923675937604457e-9, 1.0574891476389556e+24, -0.012089259922504425…

fc.float({ min: 0 });
// Note: All possible positive 32-bit floating point values (including +∞ and NaN)
// Examples of generated values: 722749030400, 9.80908925027372e-45, 4.549913925362434e+24, 4.32932694138799e-7, 3.4028224522648084e+38…

fc.float({ noDefaultInfinity: true, noNaN: true });
// Note: All possible finite 32-bit floating point values
// Examples of generated values: 0.0030062051955610514, 5.605193857299268e-45, 3.4028212353202322e+38, -2.802596928649634e-45, -160112.453125…

fc.float({ noDefaultInfinity: true, min: Number.NEGATIVE_INTEGER, max: Number.POSITIVE_INTEGER });
// Note: Same as fc.float(), noDefaultInfinity just tells that defaults for min and max
// should not be set to -∞ and +∞. It does not forbid the user to explicitely set them to -∞ and +∞.
// Examples of generated values: -5.435122013092041, 1981086548623360, -2.2481372319305137e-9, -2.5223372357846707e-44, 5.606418179297701e-30…

fc.float({ min: 0, max: 1, maxExcluded: true });
// Note: All possible 32-bit floating point values between 0 (included) and 1 (excluded)
// Examples of generated values: 3.2229864679470793e-44, 2.4012229232976108e-20, 1.1826533935374394e-27, 0.9999997615814209, 3.783505853677006e-44…

fc.float({ noInteger: true });
// Note: All possible 32-bit floating point values but no integer
// Examples of generated values: -7.006492321624085e-45, 1.4734616113175924e-21, 8.407790785948902e-45, 1.5815058151957828e-9, Number.POSITIVE_INFINITY…

fc.noBias(fc.integer({ min: 0, max: (1 << 24) - 1 }).map((v) => v / (1 << 24)));
// Note: `fc.float` does not uniformly distribute the generated values in the requested range.
// If you really want a uniform distribution of 32-bit floating point numbers in range 0 (included)
// and 1 (excluded), you may want to use the arbitrary defined right above.
// Examples of generated values: 0.06896239519119263, 0.5898661017417908, 0.7715556621551514, 0.4010099768638611, 0.8638045787811279…

Resources: API reference.
Available since 0.0.6.

double​

Floating point values.

Generate any floating point value taken into the specified range. The lower and upper bounds are included into the range of possible values.

Signatures:

  • fc.double()
  • fc.double({min?, max?, minExcluded?, maxExcluded?, noDefaultInfinity?, noNaN?, noInteger?})

with:

  • min? — default: -∞ and -Number.MAX_VALUE when noDefaultInfinity:true — lower bound for the generated 32-bit floats (included)
  • max? — default: +∞ and Number.MAX_VALUE when noDefaultInfinity:true — upper bound for the generated 32-bit floats (included)
  • minExcluded? — default: false — do not include min in the set of possible values
  • maxExcluded? — default: false — do not include max in the set of possible values
  • noDefaultInfinity? — default: false — use finite values for min and max by default
  • noNaN? — default: false — do not generate Number.NaN
  • noInteger? — default: false — do not generate values matching Number.isInteger

Usages:

fc.double();
// Note: All possible floating point values (including -∞, +∞ and NaN but also -0)
// Examples of generated values: 6.978211330273434e+123, 2.6272140589206812e-53, 947075901019127, -1.3737004055555409e-182, -4.4e-323…

fc.double({ min: 0 });
// Note: All possible positive floating point values (including +∞ and NaN)
// Examples of generated values: 8.762813623312512e-262, 5.0929130565593696e-226, 1.3411163978818024e+222, 8845029414547763, 8.4e-323…

fc.double({ noDefaultInfinity: true, noNaN: true });
// Note: All possible finite floating point values
// Examples of generated values: -3.0862366688503372e+144, -1.7384136409372626e-212, 1.7976931348623153e+308, 2.5e-323, -1.1800479468035008e+224…

fc.double({ noDefaultInfinity: true, min: Number.NEGATIVE_INTEGER, max: Number.POSITIVE_INTEGER });
// Note: Same as fc.double(), noDefaultInfinity just tells that defaults for min and max
// should not be set to -∞ and +∞. It does not forbid the user to explicitely set them to -∞ and +∞.
// Examples of generated values: 7.593633990222606e-236, -5.74664305820822e+216, -1.243100551492039e-161, 1.7976931348623143e+308, -1.7976931348623157e+308…

fc.double({ min: 0, max: 1, maxExcluded: true });
// Note: All possible floating point values between 0 (included) and 1 (excluded)
// Examples of generated values: 4.801635255684817e-73, 4.882602580683884e-55, 0.9999999999999998, 0.9999999999999991, 2.5e-323…

fc.double({ noInteger: true });
// Note: All possible floating point values but no integer
// Examples of generated values: 9.4e-323, 4503599627370491.5, -1.8524776326185756e-119, 2.5e-323, -5e-323…

fc.noBias(
  fc
    .tuple(fc.integer({ min: 0, max: (1 << 26) - 1 }), fc.integer({ min: 0, max: (1 << 27) - 1 }))
    .map((v) => (v[0] * Math.pow(2, 27) + v[1]) * Math.pow(2, -53)),
);
// Note: `fc.double` does not uniformly distribute the generated values in the requested range.
// If you really want a uniform distribution of 64-bit floating point numbers in range 0 (included)
// and 1 (excluded), you may want to use the arbitrary defined right above.
// Examples of generated values: 0.5424979085274226, 0.8984809917404123, 0.577376440989232, 0.8433714130130558, 0.48219857913738606…

Resources: API reference.
Available since 0.0.6.

Last updated on by Nicolas DUBIEN