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104 lines
3.7 KiB
Markdown
104 lines
3.7 KiB
Markdown
<!-- Note: This file is automatically generated from source code comments. Changes made in this file will be overridden. -->
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# 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, callback)
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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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- 'engineering'
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Always use engineering notation.
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For example '123.4e+0' and '14.0e+6'
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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.
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In case of notation 'fixed', `precision` defines the number of
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significant digits after the decimal point.
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`precision` is undefined by default.
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- `lowerExp: number`
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Exponent determining the lower boundary for formatting a value with
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an exponent when `notation='auto`. Default value is `-3`.
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- `upperExp: number`
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Exponent determining the upper boundary for formatting a value with
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an exponent when `notation='auto`. Default value is `5`.
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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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- `callback: function`
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A custom formatting function, invoked for all numeric elements in `value`,
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for example all elements of a matrix, or the real and imaginary
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parts of a complex number. This callback can be used to override the
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built-in numeric notation with any type of formatting. Function `callback`
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is called with `value` as parameter and must return a string.
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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(12e8, {notation: 'fixed'}) // returns '1200000000'
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math.format(2.3, {notation: 'fixed', precision: 4}) // returns '2.3000'
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math.format(52.8, {notation: 'exponential'}) // returns '5.28e+1'
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math.format(12400,{notation: 'engineering'}) // returns '12.400e+3'
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math.format(2000, {lowerExp: -2, upperExp: 2}) // returns '2e+3'
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function formatCurrency(value) {
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// return currency notation with two digits:
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return '$' + value.toFixed(2)
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// you could also use math.format inside the callback:
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// return '$' + math.format(value, {notation: 'fixed', precision: 2})
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}
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math.format([2.1, 3, 0.016], formatCurrency} // returns '[$2.10, $3.00, $0.02]'
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```
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## See also
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[print](print.md)
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