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Different forms of script execution are supported. Scripts may be evaluated from the source directly, or first compiled and then later executed. Interactive execution is also supported.

Some aspects of script execution, such as type conversions and object creation, may be accessed directly through methods of Context.
See Also:   Scriptable
author:
   Norris Boyd
author:
   Brendan Eich

The properties allow to query and set scope and prototype chains for the objects.

The function source must be a function definition as defined by ECMA (e.g., "function f(a) { return a; }").
Parameters:
  scope - the scope to compile relative to
Parameters:
  source - the function definition source
Parameters:
  sourceName - a string describing the source, such as a filename
Parameters:
  lineno - the starting line number
Parameters:
  securityDomain - an arbitrary object that specifies securityinformation about the origin or owner of the script.

Returns a script that may later be executed. Will consume all the source in the reader.
Parameters:
  in - the input reader
Parameters:
  sourceName - a string describing the source, such as a filename
Parameters:
  lineno - the starting line number for reporting errors
Parameters:
  securityDomain - an arbitrary object that specifies securityinformation about the origin or owner of the script.

Returns a script that may later be executed.
Parameters:
  source - the source string
Parameters:
  sourceName - a string describing the source, such as a filename
Parameters:
  lineno - the starting line number for reporting errors
Parameters:
  securityDomain - an arbitrary object that specifies securityinformation about the origin or owner of the script.

If the object defines a length property convertible to double number, then the number is converted Uint32 value as defined in Ecma 9.6 and Java array of that size is allocated. The array is initialized with the values obtained by calling get() on object for each value of i in [0,length-1].

Since the Context is associated with a thread it can be used to maintain values that can be later retrieved using the current thread.

Note that the values are maintained with the Context, so if the Context is disassociated from the thread the values cannot be retreived.

The default implementation calls ContextFactory.hasFeature(Context cxint featureIndex) that allows to customize Context behavior without introducing Context subclasses.

This method must be called to initialize a scope before scripts can be evaluated in that scope.

This method does not affect the Context it is called upon.
Parameters:
  scope - the scope to initialize, or null, in which case a newobject will be created to serve as the scope the initialized scope.

This method must be called to initialize a scope before scripts can be evaluated in that scope.

This method does not affect the Context it is called upon.

This form of the method also allows for creating "sealed" standard objects.

Parameters:
  scope - the scope to create the object in
Parameters:
  length - the initial length (JavaScript arrays may haveadditional properties added dynamically).

If sealKey is not null, calling Context.unseal(Object sealKey) with the same key unseals the object.

Setting the language version will affect functions and scripts compiled subsequently.

The optimization level is expected to be an integer between -1 and 9.

stringIsCompilableUnit is intended to support interactive compilation of javascript.

This is useful to define shared scope containing functions that can be called from scripts and functions using private scopes.

By default Context.hasFeature(int) returns false.
since:
   1.6 Release 1

By default Context.hasFeature(int) returns true if the current JS version is set to Context.VERSION_DEFAULT or is at least Context.VERSION_1_6 .
since:
   1.6 Release 1

By default Context.hasFeature(int) returns false.
since:
   1.6 Release 6

The properties allow to query and set scope and prototype chains for the objects. The special meaning of the properties is available only when they are used as the right hand side of the dot operator. For example, while x.__proto__ = y changes the prototype chain of the object x to point to y, x["__proto__"] = y simply assigns a new value to the property __proto__ in x even when the feature is on. By default Context.hasFeature(int) returns true.

By default Context.hasFeature(int) returns false.
since:
   1.6 Release 1

By default Context.hasFeature(int) returns false.
since:
   1.6 Release 6

By default Context.hasFeature(int) returns false.
since:
   1.6 Release 1

By default Context.hasFeature(int) returns true only if the current JS version is set to Context.VERSION_1_2 .

It is allowed to use null for factory argument in which case the factory associated with the scope will be used to create new context instances.
See Also:   ContextFactory.call(ContextAction)

The function source must be a function definition as defined by ECMA (e.g., "function f(a) { return a; }").
Parameters:
  scope - the scope to compile relative to
Parameters:
  source - the function definition source
Parameters:
  sourceName - a string describing the source, such as a filename
Parameters:
  lineno - the starting line number
Parameters:
  securityDomain - an arbitrary object that specifies securityinformation about the origin or owner of the script. Forimplementations that don't care about security, this valuemay be null. a Function that may later be called
See Also:   org.mozilla.javascript.Function

Returns a script that may later be executed. Will consume all the source in the reader.
Parameters:
  in - the input reader
Parameters:
  sourceName - a string describing the source, such as a filename
Parameters:
  lineno - the starting line number for reporting errors
Parameters:
  securityDomain - an arbitrary object that specifies securityinformation about the origin or owner of the script. Forimplementations that don't care about security, this valuemay be null. a script that may later be executed
exception:
  IOException - if an IOException was generated by the Reader
See Also:   org.mozilla.javascript.Script

Returns a script that may later be executed.
Parameters:
  source - the source string
Parameters:
  sourceName - a string describing the source, such as a filename
Parameters:
  lineno - the starting line number for reporting errors
Parameters:
  securityDomain - an arbitrary object that specifies securityinformation about the origin or owner of the script. Forimplementations that don't care about security, this valuemay be null. a script that may later be executed
See Also:   org.mozilla.javascript.Script

Decompiles a previously compiled JavaScript function object to canonical source.

Returns function body of '[native code]' if no decompilation information is available.
Parameters:
  fun - the JavaScript function to decompile
Parameters:
  indent - the number of spaces to indent the result a string representing the function source

Decompiles the body a previously compiled JavaScript Function object to canonical source, omitting the function header and trailing brace. Returns '[native code]' if no decompilation information is available.
Parameters:
  fun - the JavaScript function to decompile
Parameters:
  indent - the number of spaces to indent the result a string representing the function body source.

The canonical source of the script is returned.
Parameters:
  script - the script to decompile
Parameters:
  indent - the number of spaces to indent the result a string representing the script source

Calling enter() will return either the Context currently associated with the thread, or will create a new context and associate it with the current thread. Each call to enter() must have a matching call to exit(). For example,

 Context cx = Context.enter();
 try {
 ...
 cx.evaluateString(...);
 } finally {
 Context.exit();
 }
 

 Context.call(new ContextAction() {
 public Object run(Context cx) {
 ...
 cx.evaluateString(...);
 return null;
 }
 });
 

The same as enter() except that cx is associated with the current thread and returned if the current thread has no associated context and cx is not associated with any other thread.
Parameters:
  cx - a Context to associate with the thread if possible a Context associated with the current thread
See Also:   Context.enter()
See Also:   Context.call(ContextAction)
See Also:   ContextFactory.call(ContextAction)

the Context associated with the current thread, ornull if no context is associated with the currentthread.
See Also:   org.mozilla.javascript.Context.enter
See Also:   org.mozilla.javascript.Context.exit

If the object defines a length property convertible to double number, then the number is converted Uint32 value as defined in Ecma 9.6 and Java array of that size is allocated. The array is initialized with the values obtained by calling get() on object for each value of i in [0,length-1]. If there is not a defined value for a property the Undefined value is used to initialize the corresponding element in the array. The Java array is then returned. If the object doesn't define a length property or it is not a number, empty array is returned.
Parameters:
  object - the JavaScript array or array-like object a Java array of objects
since:
   1.4 release 2

The implementation version is of the form

 "name langVer release relNum date"
 

The language version number affects JavaScript semantics as detailed in the overview documentation. an integer that is one of VERSION_1_0, VERSION_1_1, etc.

The optimization level is expressed as an integer between -1 and 9.
since:
   1.3

Since the Context is associated with a thread it can be used to maintain values that can be later retrieved using the current thread.

Note that the values are maintained with the Context, so if the Context is disassociated from the thread the values cannot be retreived. Also, if private data is to be maintained in this manner the key should be a java.lang.Object whose reference is not divulged to untrusted code.
Parameters:
  key - the key used to lookup the value a value previously stored using putThreadLocal.

The default implementation calls ContextFactory.hasFeature(Context cxint featureIndex) that allows to customize Context behavior without introducing Context subclasses. ContextFactory documentation gives an example of hasFeature implementation.
Parameters:
  featureIndex - feature index to check true if the featureIndex feature is turned on
See Also:   Context.FEATURE_NON_ECMA_GET_YEAR
See Also:   Context.FEATURE_MEMBER_EXPR_AS_FUNCTION_NAME
See Also:   Context.FEATURE_RESERVED_KEYWORD_AS_IDENTIFIER
See Also:   Context.FEATURE_TO_STRING_AS_SOURCE
See Also:   Context.FEATURE_PARENT_PROTO_PROPRTIES
See Also:   Context.FEATURE_E4X
See Also:   Context.FEATURE_DYNAMIC_SCOPE
See Also:   Context.FEATURE_STRICT_VARS
See Also:   Context.FEATURE_STRICT_EVAL
See Also:   Context.FEATURE_LOCATION_INFORMATION_IN_ERROR
See Also:   Context.FEATURE_STRICT_MODE
See Also:   Context.FEATURE_WARNING_AS_ERROR

This method must be called to initialize a scope before scripts can be evaluated in that scope.

This method does not affect the Context it is called upon. the initialized scope

This method must be called to initialize a scope before scripts can be evaluated in that scope.

This method does not affect the Context it is called upon.
Parameters:
  scope - the scope to initialize, or null, in which case a newobject will be created to serve as the scope the initialized scope. The method returns the value of the scopeargument if it is not null or newly allocated scope object whichis an instance ScriptableObject.

This method must be called to initialize a scope before scripts can be evaluated in that scope.

This method does not affect the Context it is called upon.

This form of the method also allows for creating "sealed" standard objects. An object that is sealed cannot have properties added, changed, or removed. This is useful to create a "superglobal" that can be shared among several top-level objects. Note that sealing is not allowed in the current ECMA/ISO language specification, but is likely for the next version.
Parameters:
  scope - the scope to initialize, or null, in which case a newobject will be created to serve as the scope
Parameters:
  sealed - whether or not to create sealed standard objects thatcannot be modified. the initialized scope. The method returns the value of the scopeargument if it is not null or newly allocated scope object.
since:
   1.4R3

If value is an instance of String, Number, Boolean, Function or Scriptable, it is returned as it and will be treated as the corresponding JavaScript type of string, number, boolean, function and object.

Note that for Number instances during any arithmetic operation in JavaScript the engine will always use the result of Number.doubleValue() resulting in a precision loss if the number can not fit into double.

If value is an instance of Character, it will be converted to string of length 1 and its JavaScript type will be string.

The rest of values will be wrapped as LiveConnect objects by calling WrapFactory.wrap(Context cxScriptable scopeObject objClass staticType) as in:

 Context cx = Context.getCurrentContext();
 return cx.getWrapFactory().wrap(cx, scope, value, null);
 

Parameters:
  scope - the scope to create the object in
Parameters:
  length - the initial length (JavaScript arrays may haveadditional properties added dynamically). the new array object

The code

 Object[] args = { "a", "b" };
 newObject(scope, "Foo", args)

The instruction counting support is available only for interpreted scripts generated when the optimization level is set to -1.

The default implementation calls ContextFactory.observeInstructionCount(Context cxint instructionCount) that allows to customize Context behavior without introducing Context subclasses.
Parameters:
  instructionCount - amount of script instruction executed sincelast call to observeInstructionCount
throws:
  Error - to terminate the script
See Also:   Context.setOptimizationLevel(int)

Parameters:
  key - the key used to index the value
Parameters:
  value - the value to save

If sealKey is not null, calling Context.unseal(Object sealKey) with the same key unseals the object. If sealKey is null, unsealing is no longer possible.
See Also:   Context.isSealed()
See Also:   Context.unseal(Object)

ClassShutter may only be set if it is currently null. Otherwise a SecurityException is thrown.
Parameters:
  shutter - a ClassShutter object
throws:
  SecurityException - if there is already a ClassShutterobject for this Context

Setting the generation of debug information on will set the optimization level to zero.
since:
   1.3

Without source information, evaluating the "toString" method on JavaScript functions produces only "[native code]" for the body of the function. Note that code generated without source is not fully ECMA conformant.
since:
   1.3

Setting the language version will affect functions and scripts compiled subsequently. See the overview documentation for version-specific behavior.
Parameters:
  version - the version as specified by VERSION_1_0, VERSION_1_1, etc.

The optimization level is expected to be an integer between -1 and 9. Any negative values will be interpreted as -1, and any values greater than 9 will be interpreted as 9. An optimization level of -1 indicates that interpretive mode will always be used. Levels 0 through 9 indicate that class files may be generated. Higher optimization levels trade off compile time performance for runtime performance. The optimizer level can't be set greater than -1 if the optimizer package doesn't exist at run time.
Parameters:
  optimizationLevel - an integer indicating the level ofoptimization to perform
since:
   1.3

SecurityController may only be set if it is currently null and SecurityController.hasGlobal is false. Otherwise a SecurityException is thrown.
Parameters:
  controller - a SecurityController object
throws:
  SecurityException - if there is already a SecurityControllerobject for this Context or globally installed.
See Also:   SecurityController.initGlobal(SecurityController controller)
See Also:   SecurityController.hasGlobal

The WrapFactory allows custom object wrapping behavior for Java object manipulated with JavaScript.
See Also:   WrapFactory
since:
   1.5 Release 4

stringIsCompilableUnit is intended to support interactive compilation of javascript. If compiling the string would result in an error that might be fixed by appending more source, this method returns false. In every other case, it returns true.

Interactive shells may accumulate source lines, using this method after each new line is appended to check whether the statement being entered is complete.
Parameters:
  source - the source buffer to check whether the source is ready for compilation
since:
   1.4 Release 2

This method always throws an exception, its return value is provided only for convenience to allow a usage like:

 throw Context.throwAsScriptRuntimeEx(ex);
 

See ECMA 9.2.
Parameters:
  value - a JavaScript value the corresponding boolean value converted usingthe ECMA rules

Returns a Java double for the JavaScript Number.

See ECMA 9.3.
Parameters:
  value - a JavaScript value the corresponding double value converted usingthe ECMA rules

Note that a scope must be provided to look up the constructors for Number, Boolean, and String.

See ECMA 9.9.

Additionally, arbitrary Java objects and classes will be wrapped in a Scriptable object with its Java fields and methods reflected as JavaScript properties of the object.
Parameters:
  value - any Java object
Parameters:
  scope - global scope containing constructors for Number,Boolean, and String new JavaScript object

See ECMA 9.8.

Parameters:
  value - a JavaScript value the corresponding String value converted usingthe ECMA rules