| 1 | # Chaining
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| 2 |
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| 3 | Math.js supports chaining operations by wrapping a value into a `Chain`.
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| 4 | A chain can be created with the function `math.chain(value)`
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| 5 | (formerly `math.select(value)`).
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| 6 | All functions available in the math namespace can be executed via the chain.
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| 7 | The functions will be executed with the chain's value as the first argument,
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| 8 | followed by extra arguments provided by the function call itself.
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| 9 |
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| 10 | ```js
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| 11 | math.chain(3)
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| 12 | .add(4)
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| 13 | .subtract(2)
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| 14 | .done() // 5
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| 15 |
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| 16 | math.chain( [[1, 2], [3, 4]] )
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| 17 | .subset(math.index(0, 0), 8)
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| 18 | .multiply(3)
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| 19 | .done() // [[24, 6], [9, 12]]
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| 20 | ```
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| 21 |
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| 22 | ### API
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| 23 |
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| 24 | A `Chain` is constructed as:
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| 25 |
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| 26 | ```js
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| 27 | math.chain()
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| 28 | math.chain(value)
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| 29 | ```
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| 30 |
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| 31 | The `Chain` has all functions available in the `math` namespace, and has
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| 32 | a number of special functions:
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| 33 |
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| 34 | - `done()`
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| 35 | Finalize the chain and return the chain's value.
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| 36 | - `valueOf()`
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| 37 | The same as `done()`, returns the chain's value.
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| 38 | - `toString()`
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| 39 | Executes `math.format(value)` onto the chain's value, returning
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| 40 | a string representation of the value.
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| 41 |
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