164 lines
3.6 KiB
Markdown
164 lines
3.6 KiB
Markdown
# Number
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`Napi::Number` class is a representation of the JavaScript `Number` object. The
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`Napi::Number` class inherits its behavior from `Napi::Value` class
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(for more info see [`Napi::Value`](value.md))
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## Methods
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### Constructor
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Creates a new _empty_ instance of a `Napi::Number` object.
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```cpp
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Napi::Number();
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```
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Returns a new _empty_ `Napi::Number` object.
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### Contructor
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Creates a new instance of a `Napi::Number` object.
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```cpp
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Napi::Number(napi_env env, napi_value value);
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```
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- `[in] env`: The `napi_env` environment in which to construct the `Napi::Number` object.
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- `[in] value`: The JavaScript value holding a number.
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Returns a non-empty `Napi::Number` object.
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### New
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Creates a new instance of a `Napi::Number` object.
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```cpp
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Napi::Number Napi::Number::New(napi_env env, double value);
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```
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- `[in] env`: The `napi_env` environment in which to construct the `Napi::Number` object.
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- `[in] value`: The C++ primitive from which to instantiate the `Napi::Number`.
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Creates a new instance of a `Napi::Number` object.
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### Int32Value
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Converts a `Napi::Number` value to a `int32_t` primitive type.
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```cpp
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Napi::Number::Int32Value() const;
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```
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Returns the `int32_t` primitive type of the corresponding `Napi::Number` object.
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### Uint32Value
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Converts a `Napi::Number` value to a `uint32_t` primitive type.
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```cpp
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Napi::Number::Uint32Value() const;
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```
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Returns the `uint32_t` primitive type of the corresponding `Napi::Number` object.
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### Int64Value
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Converts a `Napi::Number` value to a `int64_t` primitive type.
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```cpp
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Napi::Number::Int64Value() const;
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```
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Returns the `int64_t` primitive type of the corresponding `Napi::Number` object.
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### FloatValue
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Converts a `Napi::Number` value to a `float` primitive type.
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```cpp
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Napi::Number::FloatValue() const;
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```
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Returns the `float` primitive type of the corresponding `Napi::Number` object.
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### DoubleValue
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Converts a `Napi::Number` value to a `double` primitive type.
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```cpp
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Napi::Number::DoubleValue() const;
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```
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Returns the `double` primitive type of the corresponding `Napi::Number` object.
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## Operators
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The `Napi::Number` class contains a set of operators to easily cast JavaScript
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`Number` object to one of the following primitive types:
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- `int32_t`
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- `uint32_t`
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- `int64_t`
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- `float`
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- `double`
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### operator int32_t
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Converts a `Napi::Number` value to a `int32_t` primitive.
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```cpp
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Napi::Number::operator int32_t() const;
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```
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Returns the `int32_t` primitive type of the corresponding `Napi::Number` object.
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### operator uint32_t
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Converts a `Napi::Number` value to a `uint32_t` primitive type.
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```cpp
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Napi::Number::operator uint32_t() const;
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```
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Returns the `uint32_t` primitive type of the corresponding `Napi::Number` object.
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### operator int64_t
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Converts a `Napi::Number` value to a `int64_t` primitive type.
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```cpp
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Napi::Number::operator int64_t() const;
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```
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Returns the `int64_t` primitive type of the corresponding `Napi::Number` object.
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### operator float
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Converts a `Napi::Number` value to a `float` primitive type.
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```cpp
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Napi::Number::operator float() const;
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```
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Returns the `float` primitive type of the corresponding `Napi::Number` object.
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### operator double
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Converts a `Napi::Number` value to a `double` primitive type.
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```cpp
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Napi::Number::operator double() const;
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```
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Returns the `double` primitive type of the corresponding `Napi::Number` object.
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### Example
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The following shows an example of casting a number to an `uint32_t` value.
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```cpp
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uint32_t operatorVal = Napi::Number::New(Env(), 10.0); // Number to unsigned 32 bit integer
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// or
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auto instanceVal = info[0].As<Napi::Number>().Uint32Value();
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```
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