QJSValue ¶

函数 ¶

Working With Arrays ¶

To create an array using QJSValue ，使用 newArray() :

// Assumes that this class was declared in QML.
QJSValue jsArray = engine->newArray(3);
												

To set individual elements in the array, use the setProperty(quint32 arrayIndex, const QJSValue &value) overload. For example, to fill the array above with integers:

for (int i = 0; i < 3; ++i) {
    jsArray.setProperty(i, QRandomGenerator::global().generate());
}
												

To determine the length of the array, access the "length" property. To access array elements, use the property(quint32 arrayIndex) overload. The following code reads the array we created above back into a list:

QVector<int> integers;
const int length = jsArray.property("length").toInt();
for (int i = 0; i < length; ++i) {
    integers.append(jsArray.property(i).toInt());
}
												

另请参阅

QJSEngine QJSValueIterator

class QJSValue ( [ value=UndefinedValue ] ) ¶

QJSValue(value)

QJSValue(other)

QJSValue(value)

QJSValue(str)

QJSValue(value)

QJSValue(value)

QJSValue(value)

param str

str

param other

QJSValue

param value

SpecialValue

构造新 QJSValue with a special value .

构造新 QJSValue with a boolean value .

构造新 QJSValue with a string value .

构造新 QJSValue with a number value .

构造新 QJSValue with a number value .

构造新 QJSValue with a number value .

PySide2.QtQml.QJSValue. SpecialValue ¶

This enum is used to specify a single-valued type.

常量	描述
QJSValue.UndefinedValue	An undefined value.
QJSValue.NullValue	A null value.

PySide2.QtQml.QJSValue. ErrorType ¶

Use this enum for JavaScript language-specific types of Error objects.

They may be useful when emulating language features in C++ requires the use of specialized exception types. In addition, they may help to more clearly communicate certain typical conditions, instead of throwing a generic JavaScript exception. For example, code that deals with networking and resource locators may find it useful to propagate errors related to malformed locators using the type.

常量	描述
QJSValue.GenericError	A generic Error object, but not of a specific sub-type.
QJSValue.RangeError	A value did not match the expected set or range.
QJSValue.ReferenceError	A non-existing variable referenced.
QJSValue.SyntaxError	An invalid token or sequence of tokens was encountered that does not conform with the syntax of the language.
QJSValue.TypeError	An operand or argument is incompatible with the type expected.
QJSValue.URIError	A URI handling function was used incorrectly or the URI provided is malformed.

PySide2.QtQml.QJSValue. call ( [ args=QJSValueList() ] ) ¶

参数

args –

返回类型

QJSValue

Calls this QJSValue as a function, passing args as arguments to the function, and using the globalObject() as the “this”-object. Returns the value returned from the function.

若此 QJSValue is not callable, does nothing and returns an undefined QJSValue .

Calling can cause an exception to occur in the script engine; in that case, returns the value that was thrown (typically an Error object). You can call isError() on the return value to determine whether an exception occurred.

另请参阅

isCallable() callWithInstance() callAsConstructor()

PySide2.QtQml.QJSValue. callAsConstructor ( [ args=QJSValueList() ] ) ¶

参数

args –

返回类型

QJSValue

创建新 Object and calls this QJSValue as a constructor, using the created object as the `this’ object and passing args as arguments. If the return value from the constructor call is an object, then that object is returned; otherwise the default constructed object is returned.

若此 QJSValue is not a function, does nothing and returns an undefined QJSValue .

Calling this function can cause an exception to occur in the script engine; in that case, the value that was thrown (typically an Error object) is returned. You can call isError() on the return value to determine whether an exception occurred.

另请参阅

call() newObject()

PySide2.QtQml.QJSValue. callWithInstance ( instance [ , args=QJSValueList() ] ) ¶

参数

• instance – QJSValue

• args –

返回类型

QJSValue

Calls this QJSValue as a function, using instance as the `this’ object in the function call, and passing args as arguments to the function. Returns the value returned from the function.

若此 QJSValue is not a function, call() does nothing and returns an undefined QJSValue .

注意：若 instance is not an object, the global object (see globalObject() ) will be used as the `this’ object.

调用 call() can cause an exception to occur in the script engine; in that case, call() returns the value that was thrown (typically an Error object). You can call isError() on the return value to determine whether an exception occurred.

另请参阅

call()

PySide2.QtQml.QJSValue. deleteProperty ( name ) ¶

参数

name – unicode

返回类型

bool

Attempts to delete this object’s property of the given name . Returns true if the property was deleted, otherwise returns false.

The behavior of this function is consistent with the JavaScript delete operator. In particular:

• Non-configurable properties cannot be deleted.

• This function will return true even if this object doesn’t have a property of the given name (i.e., non-existent properties are “trivially deletable”).

• If this object doesn’t have an own property of the given name , but an object in the prototype() chain does, the prototype object’s property is not deleted, and this function returns true.

另请参阅

setProperty() hasOwnProperty()

PySide2.QtQml.QJSValue. engine ( ) ¶

返回类型

QJSEngine

注意

此函数被弃用。

返回 QJSEngine that created this QJSValue , or 0 if this QJSValue is invalid or the value is not associated with a particular engine.

PySide2.QtQml.QJSValue. 等于 ( other ) ¶

参数

other – QJSValue

返回类型

bool

返回 true，若此 QJSValue 等于 other , otherwise returns false. The comparison follows the behavior described in ECMA-262 section 11.9.3, “The Abstract Equality Comparison Algorithm”.

This function can return true even if the type of this QJSValue is different from the type of the other value; i.e. the comparison is not strict. For example, comparing the number 9 to the string “9” returns true; comparing an undefined value to a null value returns true; comparing a Number object whose primitive value is 6 to a 字符串 object whose primitive value is “6” returns true; and comparing the number 1 to the boolean value true returns true. If you want to perform a comparison without such implicit value conversion, use strictlyEquals() .

Note that if this QJSValue 或 other value are objects, calling this function has side effects on the script engine, since the engine will call the object’s valueOf() function (and possibly toString() ) in an attempt to convert the object to a primitive value (possibly resulting in an uncaught script exception).

另请参阅

strictlyEquals()

PySide2.QtQml.QJSValue. errorType ( ) ¶

返回类型

ErrorType

Returns the error type this QJSValue represents if it is an Error object. Otherwise, returns NoError."

另请参阅

isError() QJSEngine - Script 异常

PySide2.QtQml.QJSValue. hasOwnProperty ( name ) ¶

参数

name – unicode

返回类型

bool

Returns true if this object has an own (not prototype-inherited) property of the given name ，否则返回 false。

另请参阅

property() hasProperty()

PySide2.QtQml.QJSValue. hasProperty ( name ) ¶

参数

name – unicode

返回类型

bool

Returns true if this object has a property of the given name ，否则返回 false。

另请参阅

property() hasOwnProperty()

PySide2.QtQml.QJSValue. isArray ( ) ¶

返回类型

bool

返回 true，若此 QJSValue is an object of the Array class; otherwise returns false.

另请参阅

newArray()

PySide2.QtQml.QJSValue. isBool ( ) ¶

返回类型

bool

返回 true，若此 QJSValue is of the primitive type Boolean; otherwise returns false.

另请参阅

toBool()

PySide2.QtQml.QJSValue. isCallable ( ) ¶

返回类型

bool

返回 true，若此 QJSValue can be called a function, otherwise returns false.

另请参阅

call()

PySide2.QtQml.QJSValue. isDate ( ) ¶

返回类型

bool

返回 true，若此 QJSValue is an object of the Date class; otherwise returns false.

PySide2.QtQml.QJSValue. isError ( ) ¶

返回类型

bool

返回 true，若此 QJSValue is an object of the Error class; otherwise returns false.

另请参阅

errorType() QJSEngine - Script 异常

PySide2.QtQml.QJSValue. isNull ( ) ¶

返回类型

bool

返回 true，若此 QJSValue is of the primitive type Null; otherwise returns false.

PySide2.QtQml.QJSValue. isNumber ( ) ¶

返回类型

bool

返回 true，若此 QJSValue is of the primitive type Number; otherwise returns false.

另请参阅

toNumber()

PySide2.QtQml.QJSValue. isObject ( ) ¶

返回类型

bool

返回 true，若此 QJSValue is of the Object type; otherwise returns false.

Note that function values, variant values, and QObject values are objects, so this function returns true for such values.

另请参阅

newObject()

PySide2.QtQml.QJSValue. isQMetaObject ( ) ¶

返回类型

bool

返回 true，若此 QJSValue 是 QMetaObject ；否则返回 false。

另请参阅

toQMetaObject() newQMetaObject()

PySide2.QtQml.QJSValue. isQObject ( ) ¶

返回类型

bool

返回 true，若此 QJSValue 是 QObject ；否则返回 false。

Note: This function returns true even if the QObject that this QJSValue wraps has been deleted.

另请参阅

toQObject() newQObject()

PySide2.QtQml.QJSValue. isRegExp ( ) ¶

返回类型

bool

返回 true，若此 QJSValue is an object of the RegExp class; otherwise returns false.

PySide2.QtQml.QJSValue. isString ( ) ¶

返回类型

bool

返回 true，若此 QJSValue is of the primitive type String; otherwise returns false.

另请参阅

toString()

PySide2.QtQml.QJSValue. isUndefined ( ) ¶

返回类型

bool

返回 true，若此 QJSValue is of the primitive type Undefined; otherwise returns false.

PySide2.QtQml.QJSValue. isVariant ( ) ¶

返回类型

bool

返回 true，若此 QJSValue is a variant value; otherwise returns false.

另请参阅

toVariant()

PySide2.QtQml.QJSValue. 特性 ( name ) ¶

参数

name – unicode

返回类型

QJSValue

PySide2.QtQml.QJSValue. 特性 ( arrayIndex ) ¶

参数

arrayIndex – quint32

返回类型

QJSValue

这是重载函数。

Returns the property at the given arrayIndex .

It is possible to access elements in an array in two ways. The first is to use the array index as the property name:

qDebug() << jsValueArray.property(QLatin1String("4")).toString();
												

The second is to use the overload that takes an index:

qDebug() << jsValueArray.property(4).toString();
												

Both of these approaches achieve the same result, except that the latter:

• Is easier to use (can use an integer directly)

• Is faster (no conversion to integer)

若此 QJSValue is not an Array object, this function behaves as if property() was called with the string representation of arrayIndex .

PySide2.QtQml.QJSValue. prototype ( ) ¶

返回类型

QJSValue

若此 QJSValue is an object, returns the internal prototype ( __proto__ property) of this object; otherwise returns an undefined QJSValue .

另请参阅

setPrototype() isObject()

PySide2.QtQml.QJSValue. setProperty ( arrayIndex , value ) ¶

参数

• arrayIndex – quint32

• value – QJSValue

PySide2.QtQml.QJSValue. setProperty ( name , value ) ¶

参数

• name – unicode

• value – QJSValue

PySide2.QtQml.QJSValue. setPrototype ( prototype ) ¶

参数

prototype – QJSValue

若此 QJSValue is an object, sets the internal prototype ( __proto__ property) of this object to be prototype ; if the QJSValue is null, it sets the prototype to null; otherwise does nothing.

The internal prototype should not be confused with the public property with name “prototype”; the public prototype is usually only set on functions that act as constructors.

另请参阅

prototype() isObject()

PySide2.QtQml.QJSValue. strictlyEquals ( other ) ¶

参数

other – QJSValue

返回类型

bool

返回 true，若此 QJSValue 等于 other using strict comparison (no conversion), otherwise returns false. The comparison follows the behavior described in ECMA-262 section 11.9.6, “The Strict Equality Comparison Algorithm”.

If the type of this QJSValue is different from the type of the other value, this function returns false. If the types are equal, the result depends on the type, as shown in the following table:

Type	结果
Undefined	true
Null	true
布尔	true if both values are true, false otherwise
Number	false if either value is NaN (Not-a-Number); true if values are equal, false otherwise
字符串	true if both values are exactly the same sequence of characters, false otherwise
Object	true if both values refer to the same object, false otherwise

另请参阅

equals()

PySide2.QtQml.QJSValue. toBool ( ) ¶

返回类型

bool

Returns the boolean value of this QJSValue , using the conversion rules described in ECMA-262 section 9.2, “ToBoolean”.

Note that if this QJSValue is an object, calling this function has side effects on the script engine, since the engine will call the object’s valueOf() function (and possibly toString() ) in an attempt to convert the object to a primitive value (possibly resulting in an uncaught script exception).

另请参阅

isBool()

PySide2.QtQml.QJSValue. toDateTime ( ) ¶

返回类型

QDateTime

返回 QDateTime representation of this value, in local time. If this QJSValue is not a date, or the value of the date is NaN (Not-a-Number), an invalid QDateTime 被返回。

另请参阅

isDate()

PySide2.QtQml.QJSValue. toInt ( ) ¶

返回类型

qint32

Returns the signed 32-bit integer value of this QJSValue , using the conversion rules described in ECMA-262 section 9.5, “ToInt32”.

Note that if this QJSValue is an object, calling this function has side effects on the script engine, since the engine will call the object’s valueOf() function (and possibly toString() ) in an attempt to convert the object to a primitive value (possibly resulting in an uncaught script exception).

另请参阅

toNumber() toUInt()

PySide2.QtQml.QJSValue. toNumber ( ) ¶

返回类型

double

Returns the number value of this QJSValue , as defined in ECMA-262 section 9.3, “ToNumber”.

Note that if this QJSValue is an object, calling this function has side effects on the script engine, since the engine will call the object’s valueOf() function (and possibly toString() ) in an attempt to convert the object to a primitive value (possibly resulting in an uncaught script exception).

另请参阅

isNumber() toInt() toUInt()

PySide2.QtQml.QJSValue. toQMetaObject ( ) ¶

返回类型

QMetaObject

* If this QJSValue 是 QMetaObject , returns the QMetaObject pointer * that the QJSValue represents; otherwise, returns None . * *

另请参阅

isQMetaObject()

PySide2.QtQml.QJSValue. toQObject ( ) ¶

返回类型

QObject

若此 QJSValue 是 QObject , returns the QObject pointer that the QJSValue represents; otherwise, returns None .

若 QObject that this QJSValue wraps has been deleted, this function returns None (i.e. it is possible for to return None even when isQObject() returns true).

另请参阅

isQObject()

PySide2.QtQml.QJSValue. toString ( ) ¶

返回类型

unicode

Returns the string value of this QJSValue , as defined in ECMA-262 section 9.8, “ToString”.

Note that if this QJSValue is an object, calling this function has side effects on the script engine, since the engine will call the object’s function (and possibly valueOf()) in an attempt to convert the object to a primitive value (possibly resulting in an uncaught script exception).

另请参阅

isString()

PySide2.QtQml.QJSValue. toUInt ( ) ¶

返回类型

quint32

Returns the unsigned 32-bit integer value of this QJSValue , using the conversion rules described in ECMA-262 section 9.6, “ToUint32”.

Note that if this QJSValue is an object, calling this function has side effects on the script engine, since the engine will call the object’s valueOf() function (and possibly toString() ) in an attempt to convert the object to a primitive value (possibly resulting in an uncaught script exception).

另请参阅

toNumber() toInt()

PySide2.QtQml.QJSValue. toVariant ( ) ¶

返回类型

object

返回 QVariant value of this QJSValue , if it can be converted to a QVariant ; otherwise returns an invalid QVariant . The conversion is performed according to the following table:

Input Type	结果
Undefined	An invalid QVariant .
Null	A QVariant containing a null pointer ( Nullptr ).
布尔	A QVariant containing the value of the boolean.
Number	A QVariant containing the value of the number.
字符串	A QVariant containing the value of the string.
QVariant Object	The result is the QVariant value of the object (no conversion).
QObject Object	A QVariant containing a pointer to the QObject .
Date Object	A QVariant containing the date value ( toDateTime() ).
RegExp Object	A QVariant containing the regular expression value.
Array Object	The array is converted to a QVariantList . Each element is converted to a QVariant , recursively; cyclic references are not followed.
Object	The object is converted to a QVariantMap . Each property is converted to a QVariant , recursively; cyclic references are not followed.

另请参阅

isVariant()