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Debugger: Difference between revisions
→Accessor Properties of the Debugger.Frame Prototype Object: Specify that the frame is given as 'this' to onStep and onPop.
(→Resumption Values: 'return' resumption values can't force 'new' expressions to return non-objects.) |
(→Accessor Properties of the Debugger.Frame Prototype Object: Specify that the frame is given as 'this' to onStep and onPop.) |
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<dt>onStep | <dt>onStep | ||
<dd>This property must be either <code>undefined</code> or a function. If it is a function, SpiderMonkey calls it | <dd>This property must be either <code>undefined</code> or a function. If it is a function, SpiderMonkey calls it when execution in this frame makes a small amount of progress, passing no arguments and providing this <code>Debugger.Frame</code> instance as the <code>this</code>value. The function should return a [[#Resumption_Values|resumption value]] specifying how the debuggee's execution should proceed. | ||
What constitutes "a small amount of progress" varies depending on the implementation, but it is fine-grained enough to implement useful "step" and "next" behavior. | What constitutes "a small amount of progress" varies depending on the implementation, but it is fine-grained enough to implement useful "step" and "next" behavior. | ||
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<dt>onPop | <dt>onPop | ||
<dd>This property must be either <code>undefined</code> or a function. If it is a function, SpiderMonkey calls it just before this frame is popped, passing a [[#Completion_Values|completion value]] indicating how this frame's execution completed. The function should return a [[#Resumption_Values|resumption value]] indicating how execution should proceed. On newly created frames, this property's value is <code>undefined</code>. | <dd>This property must be either <code>undefined</code> or a function. If it is a function, SpiderMonkey calls it just before this frame is popped, passing a [[#Completion_Values|completion value]] indicating how this frame's execution completed, and providing this <code>Debugger.Frame</code> instance as the <code>this</code> value. The function should return a [[#Resumption_Values|resumption value]] indicating how execution should proceed. On newly created frames, this property's value is <code>undefined</code>. | ||
Calls to frames' <code>onPop</code> handlers are cross-compartment, intra-thread calls: an <code>onPop</code> function must be in the debugger's compartment (and thus calls to it take place in the debugger's compartment), and the call takes place in the thread to which the frame belongs. | Calls to frames' <code>onPop</code> handlers are cross-compartment, intra-thread calls: an <code>onPop</code> function must be in the debugger's compartment (and thus calls to it take place in the debugger's compartment), and the call takes place in the thread to which the frame belongs. | ||