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Value

Napi::Value is the C++ manifestation of a JavaScript value.

Value is a the base class upon which other JavaScript values such as Number, Boolean, String, and Object are based.

The following classes inherit, either directly or indirectly, from Napi::Value:

Methods

Empty Constructor

Napi::Value::Value();

Creates a new empty Napi::Value instance.

Constructor

Napi::Value::Value(napi_env env, napi_value value);

  • [in] env: The napi_env environment in which to construct the Napi::Value object.

  • [in] value: The C++ primitive from which to instantiate the Napi::Value. value may be any of:

    • bool
    • Any integer type
    • Any floating point type
    • const char* (encoded using UTF-8, null-terminated)
    • const char16_t* (encoded using UTF-16-LE, null-terminated)
    • std::string (encoded using UTF-8)
    • std::u16string
    • Napi::Value
    • napi_value

From

template <typename T> static Napi::Value Napi::Value::From(napi_env env, const T& value);

  • [in] env: The napi_env environment in which to create the Napi::Value object.

  • [in] value: The N-API primitive value from which to create the Napi::Value object.

Returns a Napi::Value object from an N-API primitive value.

operator napi_value

operator napi_value() const;

Returns this Value's N-API value primitive.

Returns nullptr if this Napi::Value is empty.

operator ==

bool Napi::Value::operator ==(const Napi::Value& other) const;
  • [in] other: The Napi::Value object to be compared.

Returns a bool indicating if this Napi::Value strictly equals another Napi::Value.

operator !=

bool Napi::Value::operator !=(const Napi::Value& other) const;
  • [in] other: The Napi::Value object to be compared.

Returns a bool indicating if this Napi::Value does not strictly equal another Napi::Value.

StrictEquals

bool Napi::Value::StrictEquals(const Napi::Value& other) const;
  • [in] other: The Napi::Value object to be compared.

Returns a bool indicating if this Napi::Value strictly equals another Napi::Value.

Env

Napi::Env Napi::Value::Env() const;

Returns the Napi::Env environment this value is associated with.

IsEmpty

bool Napi::Value::IsEmpty() const;

Returns a bool indicating if this Napi::Value is empty (uninitialized).

An empty Napi::Value is invalid, and most attempts to perform an operation on an empty Value will result in an exception. Note an empty Napi::Value is distinct from JavaScript null or undefined, which are valid values.

When C++ exceptions are disabled at compile time, a method with a Napi::Value return type may return an empty Value to indicate a pending exception. So when not using C++ exceptions, callers should check whether this Napi::Value is empty before attempting to use it.

Type

napi_valuetype Napi::Value::Type() const;

Returns the napi_valuetype type of the Napi::Value.

IsUndefined

bool Napi::Value::IsUndefined() const;

Returns a bool indicating if this Napi::Value is an undefined JavaScript value.

IsNull

bool Napi::Value::IsNull() const;

Returns a bool indicating if this Napi::Value is a null JavaScript value.

IsBoolean

bool Napi::Value::IsBoolean() const;

Returns a bool indicating if this Napi::Value is a JavaScript boolean.

IsNumber

bool Napi::Value::IsNumber() const;

Returns a bool indicating if this Napi::Value is a JavaScript number.

IsString

bool Napi::Value::IsString() const;

Returns a bool indicating if this Napi::Value is a JavaScript string.

IsSymbol

bool Napi::Value::IsSymbol() const;

Returns a bool indicating if this Napi::Value is a JavaScript symbol.

IsArray

bool Napi::Value::IsArray() const;

Returns a bool indicating if this Napi::Value is a JavaScript array.

IsArrayBuffer

bool Napi::Value::IsArrayBuffer() const;

Returns a bool indicating if this Napi::Value is a JavaScript array buffer.

IsTypedArray

bool Napi::Value::IsTypedArray() const;

Returns a bool indicating if this Napi::Value is a JavaScript typed array.

IsObject

bool Napi::Value::IsObject() const;

Returns a bool indicating if this Napi::Value is JavaScript object.

IsFunction

bool Napi::Value::IsFunction() const;

Returns a bool indicating if this Napi::Value is a JavaScript function.

IsBuffer

bool Napi::Value::IsBuffer() const;

Returns a bool indicating if this Napi::Value is a Node buffer.

As

template <typename T> T Napi::Value::As() const;

Casts to another type of Napi::Value, when the actual type is known or assumed.

This conversion does not coerce the type. Calling any methods inappropriate for the actual value type will throw Napi::Error.

ToBoolean

Napi::Boolean Napi::Value::ToBoolean() const;

Returns the Napi::Value coerced to a JavaScript boolean.

ToNumber

Napi::Number Napi::Value::ToNumber() const;

Returns the Napi::Value coerced to a JavaScript number.

ToString

Napi::String Napi::Value::ToString() const;

Returns the Napi::Value coerced to a JavaScript string.

ToObject

Napi::Object Napi::Value::ToObject() const;

Returns the Napi::Value coerced to a JavaScript object.