Debugger.Environment instance represents a lexical environment, associating names with variables. Each
Debugger.Frame instance representing a debuggee frame has an associated environment object describing the variables in scope in that frame; and each
Debugger.Object instance representing a debuggee function has an environment object representing the environment the function has closed over.
ECMAScript environments form a tree, in which each local environment is parented by its enclosing environment (in ECMAScript terms, its ‘outer’ environment). We say an environmentbinds an identifier if that environment itself associates the identifier with a variable, independently of its outer environments. We say an identifier isin scope in an environment if the identifier is bound in that environment or any enclosing environment.
Debugger.Environment instances as needed as the debugger inspects stack frames and function objects; calling
Debugger.Environment as a function or constructor raises a
SpiderMonkey creates exactly one
Debugger.Environment instance for each environment it presents via a given
Debugger instance: if the debugger encounters the same environment through two different routes (perhaps two functions have closed over the same environment), SpiderMonkey presents the same
Debugger.Environment instance to the debugger each time. This means that the debugger can use the
== operator to recognize when two
Debugger.Environment instances refer to the same environment in the debuggee, and place its own properties on a
Debugger.Environment instance to store metadata about particular environments.
(If more than one
Debugger instance is debugging the same code, each
Debugger gets a separate
Debugger.Environment instance for a given environment. This allows the code using each
Debugger instance to place whatever properties it likes on its own
Debugger.Object instances, without worrying about interfering with other debuggers.)
Debugger.Environment instance’s referent is not a debuggee environment, then attempting to access its properties (other than
inspectable) or call any its methods throws an instance of
Debugger.Environment instances protect their referents from the garbage collector; as long as the
Debugger.Environment instance is live, the referent remains live. Garbage collection has no visible effect on
Accessor Properties of the Debugger.Environment Prototype Object
Debugger.Environment instance inherits the following accessor properties from its prototype:
- True if this environment is a debuggee environment, and can therefore be inspected. False otherwise. All other properties and methods of
Debugger.Environmentinstances throw if applied to a non-inspectable environment.
The type of this environment object, one of the following values:
“declarative”, indicating that the environment is a declarative environment record. Function calls, calls to
catchblocks, and the like create declarative environment records.
“object”, indicating that the environment’s bindings are the properties of an object. The global object and DOM elements appear in the chain of environments via object environments. (Note that
withstatements have their own environment type.)
“with”, indicating that the environment was introduced by a
- The environment that encloses this one (the “outer” environment, in ECMAScript terminology), or
nullif this is the outermost environment.
Debugger.Objectinstance referring to the object whose properties this environment reflects. If this is a declarative environment record, this accessor throws a
TypeError(since declarative environment records have no such object). Both
objectproperties that provide the object whose properties they reflect as variable bindings.
- If this environment represents the variable environment (the top-level environment within the function, which receives
vardefinitions) for a call to a functionf, then this property’s value is a
Debugger.Objectinstance referring tof. Otherwise, this property’s value is
- True if this environment is optimized out. False otherwise. For example, functions whose locals are never aliased may present optimized-out environments. When true,
optimizedOutproperty is true on all bindings, and
Function Properties of the Debugger.Environment Prototype Object
The methods described below may only be called with a
this value referring to a
Debugger.Environment instance; they may not be used as methods of other kinds of objects.
- Return an array of strings giving the names of the identifiers bound by this environment. The result does not include the names of identifiers bound by enclosing environments.
Return the value of the variable bound toname in this environment, or
undefinedif this environment does not bindname.Name must be a string that is a valid ECMAScript identifier name. The result is a debuggee value.
This is not an invocation function; if this call would cause debuggee code to run (say, because the environment is a
"with"environment, andname refers to an accessor property of the
withstatement’s operand), this call throws a
Storevalue as the value of the variable bound toname in this environment.Name must be a string that is a valid ECMAScript identifier name;value must be a debuggee value.
If this environment binds no variable namedname, throw a
- Return a reference to the innermost environment, starting with this environment, that bindsname. Ifname is not in scope in this environment, return
null.Name must be a string whose value is a valid ECMAScript identifier name.
- Generated from file: