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87 lines
3.0 KiB
Markdown
87 lines
3.0 KiB
Markdown
# Function format
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Format a value of any type into a string.
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## Syntax
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```js
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math.format(value)
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math.format(value, options)
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math.format(value, precision)
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math.format(value, fn)
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```
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### Where
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- `value: *`
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The value to be formatted
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- `options: Object`
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An object with formatting options. Available options:
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- `notation: string`
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Number notation. Choose from:
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- 'fixed'
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Always use regular number notation.
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For example '123.40' and '14000000'
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- 'exponential'
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Always use exponential notation.
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For example '1.234e+2' and '1.4e+7'
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- 'auto' (default)
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Regular number notation for numbers having an absolute value between
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`lower` and `upper` bounds, and uses exponential notation elsewhere.
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Lower bound is included, upper bound is excluded.
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For example '123.4' and '1.4e7'.
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- `precision: number`
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A number between 0 and 16 to round the digits of the number. In case
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of notations 'exponential' and 'auto', `precision` defines the total
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number of significant digits returned and is undefined by default.
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In case of notation 'fixed', `precision` defines the number of
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significant digits after the decimal point, and is 0 by default.
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- `exponential: Object`
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An object containing two parameters, {number} lower and {number} upper,
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used by notation 'auto' to determine when to return exponential
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notation. Default values are `lower=1e-3` and `upper=1e5`. Only
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applicable for notation `auto`.
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- `fraction: string`. Available values: 'ratio' (default) or 'decimal'.
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For example `format(fraction(1, 3))` will output '1/3' when 'ratio' is
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configured, and will output `0.(3)` when 'decimal' is configured.
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- `fn: Function`
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A custom formatting function. Can be used to override the built-in notations.
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Function `fn` is called with `value` as parameter and must return a string.
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Is useful for example to format all values inside a matrix in a particular way.
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### Parameters
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Parameter | Type | Description
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--------- | ---- | -----------
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`value` | * | Value to be stringified
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`options` | Object | Function | number | Formatting options
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### Returns
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Type | Description
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---- | -----------
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string | The formatted value
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## Examples
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```js
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math.format(6.4); // returns '6.4'
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math.format(1240000); // returns '1.24e6'
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math.format(1/3); // returns '0.3333333333333333'
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math.format(1/3, 3); // returns '0.333'
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math.format(21385, 2); // returns '21000'
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math.format(12.071, {notation: 'fixed'}); // returns '12'
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math.format(2.3, {notation: 'fixed', precision: 2}); // returns '2.30'
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math.format(52.8, {notation: 'exponential'}); // returns '5.28e+1'
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```
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## See also
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[print](print.md)
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