Enum JsValue

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pub enum JsValue {
    Null,
    Undefined,
    Boolean(bool),
    String(JsString),
    Rational(f64),
    Integer(i32),
    BigInt(JsBigInt),
    Object(JsObject),
    Symbol(JsSymbol),
}

Expand description

A Javascript value

Variants§

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Null

null - A null value, for when a value doesn’t exist.

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Undefined

undefined - An undefined value, for when a field or index doesn’t exist.

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Boolean(bool)

boolean - A true / false value, for if a certain criteria is met.

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String(JsString)

String - A UTF-8 string, such as "Hello, world".

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Rational(f64)

Number - A 64-bit floating point number, such as 3.1415

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Integer(i32)

Number - A 32-bit integer, such as 42.

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BigInt(JsBigInt)

BigInt - holds any arbitrary large signed integer.

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Object(JsObject)

Object - An object, such as Math, represented by a binary tree of string keys to Javascript values.

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Implementations§

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impl JsValue

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pub fn strict_equals(&self, other: &Self) -> bool

Strict equality comparison.

This method is executed when doing strict equality comparisons with the === operator. For more information, check https://tc39.es/ecma262/#sec-strict-equality-comparison.

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pub fn equals(&self, other: &Self, context: &mut Context) -> JsResult<bool>

Abstract equality comparison.

This method is executed when doing abstract equality comparisons with the == operator. For more information, check https://tc39.es/ecma262/#sec-abstract-equality-comparison

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pub fn same_value(x: &JsValue, y: &JsValue) -> bool

The internal comparison abstract operation SameValue(x, y), where x and y are ECMAScript language values, produces true or false.

More information:

ECMAScript

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pub fn same_value_zero(x: &JsValue, y: &JsValue) -> bool

The internal comparison abstract operation SameValueZero(x, y), where x and y are ECMAScript language values, produces true or false.

SameValueZero differs from SameValue only in its treatment of +0 and -0.

More information:

ECMAScript

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pub fn abstract_relation( &self, other: &Self, left_first: bool, context: &mut Context, ) -> JsResult<AbstractRelation>

Abstract relational comparison

The comparison x < y, where x and y are values, produces true, false, or undefined (which indicates that at least one operand is NaN).

In addition to x and y the algorithm takes a Boolean flag named LeftFirst as a parameter. The flag is used to control the order in which operations with potentially visible side-effects are performed upon x and y. It is necessary because ECMAScript specifies left to right evaluation of expressions. The default value of LeftFirst is true and indicates that the x parameter corresponds to an expression that occurs to the left of the y parameter’s corresponding expression.

If LeftFirst is false, the reverse is the case and operations must be performed upon y before x.

More Information:

ECMAScript reference

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pub fn lt(&self, other: &Self, context: &mut Context) -> JsResult<bool>

The less than operator (<) returns true if the left operand is less than the right operand, and false otherwise.

More Information:

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pub fn le(&self, other: &Self, context: &mut Context) -> JsResult<bool>

The less than or equal operator (<=) returns true if the left operand is less than or equal to the right operand, and false otherwise.

More Information:

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pub fn gt(&self, other: &Self, context: &mut Context) -> JsResult<bool>

The greater than operator (>) returns true if the left operand is greater than the right operand, and false otherwise.

More Information:

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pub fn ge(&self, other: &Self, context: &mut Context) -> JsResult<bool>

The greater than or equal operator (>=) returns true if the left operand is greater than or equal to the right operand, and false otherwise.

More Information:

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impl JsValue

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pub fn get_type(&self) -> Type

Get the type of a value

This is the abstract operation Type(v), as described in https://tc39.es/ecma262/multipage/ecmascript-data-types-and-values.html#sec-ecmascript-language-types.

Check JsValue::type_of if you need to call the typeof operator.

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impl JsValue

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pub fn new<T>(value: T) -> Self
where T: Into<Self>,

Create a new JsValue.

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pub fn undefined() -> Self

Creates a new undefined value.

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pub fn null() -> Self

Creates a new null value.

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pub fn nan() -> Self

Creates a new number with NaN value.

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pub fn positive_inifnity() -> Self

Creates a new number with Infinity value.

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pub fn negative_inifnity() -> Self

Creates a new number with -Infinity value.

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pub fn is_object(&self) -> bool

Returns true if the value is an object

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pub fn as_object(&self) -> Option<JsObject>

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pub fn is_symbol(&self) -> bool

Returns true if the value is a symbol.

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pub fn as_symbol(&self) -> Option<JsSymbol>

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pub fn is_function(&self) -> bool

Returns true if the value is a function

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pub fn is_undefined(&self) -> bool

Returns true if the value is undefined.

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pub fn is_null(&self) -> bool

Returns true if the value is null.

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pub fn is_null_or_undefined(&self) -> bool

Returns true if the value is null or undefined.

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pub fn is_double(&self) -> bool

Returns true if the value is a 64-bit floating-point number.

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pub fn is_integer(&self) -> bool

Returns true if the value is integer.

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pub fn is_number(&self) -> bool

Returns true if the value is a number.

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pub fn as_number(&self) -> Option<f64>

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pub fn is_string(&self) -> bool

Returns true if the value is a string.

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pub fn as_string(&self) -> Option<&JsString>

Returns the string if the values is a string, otherwise None.

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pub fn is_boolean(&self) -> bool

Returns true if the value is a boolean.

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pub fn as_boolean(&self) -> Option<bool>

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pub fn is_bigint(&self) -> bool

Returns true if the value is a bigint.

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pub fn as_bigint(&self) -> Option<&JsBigInt>

Returns an optional reference to a BigInt if the value is a BigInt primitive.

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pub fn to_boolean(&self) -> bool

Converts the value to a bool type.

More information:

ECMAScript

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pub fn set_data(&self, data: ObjectData)

Set the kind of an object.

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pub fn to_primitive( &self, context: &mut Context, preferred_type: PreferredType, ) -> JsResult<JsValue>

The abstract operation ToPrimitive takes an input argument and an optional argument PreferredType.

https://tc39.es/ecma262/#sec-toprimitive

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pub fn to_bigint(&self, context: &mut Context) -> JsResult<JsBigInt>

Converts the value to a BigInt.

This function is equivelent to BigInt(value) in JavaScript.

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pub fn display(&self) -> ValueDisplay<'_>

Returns an object that implements Display.

§Examples

use boa::JsValue;

let value = JsValue::new(3);

println!("{}", value.display());

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pub fn to_string(&self, context: &mut Context) -> JsResult<JsString>

Converts the value to a string.

This function is equivalent to String(value) in JavaScript.

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pub fn to_object(&self, context: &mut Context) -> JsResult<JsObject>

Converts the value to an Object.

This function is equivalent to Object(value) in JavaScript

See: https://tc39.es/ecma262/#sec-toobject

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pub fn to_property_key(&self, context: &mut Context) -> JsResult<PropertyKey>

Converts the value to a PropertyKey, that can be used as a key for properties.

See https://tc39.es/ecma262/#sec-topropertykey

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pub fn to_numeric(&self, context: &mut Context) -> JsResult<Numeric>

It returns value converted to a numeric value of type Number or BigInt.

See: https://tc39.es/ecma262/#sec-tonumeric

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pub fn to_u32(&self, context: &mut Context) -> JsResult<u32>

Converts a value to an integral 32 bit unsigned integer.

This function is equivalent to value | 0 in JavaScript

See: https://tc39.es/ecma262/#sec-touint32

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pub fn to_i32(&self, context: &mut Context) -> JsResult<i32>

Converts a value to an integral 32 bit signed integer.

See: https://tc39.es/ecma262/#sec-toint32

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pub fn to_index(&self, context: &mut Context) -> JsResult<usize>

Converts a value to a non-negative integer if it is a valid integer index value.

See: https://tc39.es/ecma262/#sec-toindex

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pub fn to_length(&self, context: &mut Context) -> JsResult<usize>

Converts argument to an integer suitable for use as the length of an array-like object.

See: https://tc39.es/ecma262/#sec-tolength

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pub fn to_integer(&self, context: &mut Context) -> JsResult<f64>

Converts a value to an integral Number value.

See: https://tc39.es/ecma262/#sec-tointeger

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pub fn to_number(&self, context: &mut Context) -> JsResult<f64>

Converts a value to a double precision floating point.

This function is equivalent to the unary + operator (+value) in JavaScript

See: https://tc39.es/ecma262/#sec-tonumber

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pub fn to_numeric_number(&self, context: &mut Context) -> JsResult<f64>

This is a more specialized version of to_numeric, including BigInt.

This function is equivalent to Number(value) in JavaScript

See: https://tc39.es/ecma262/#sec-tonumeric

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pub fn require_object_coercible( &self, context: &mut Context, ) -> JsResult<&JsValue>

Check if the Value can be converted to an Object

The abstract operation RequireObjectCoercible takes argument argument. It throws an error if argument is a value that cannot be converted to an Object using ToObject. It is defined by Table 15

More information: