The Tor Browser: comparison js/src/doc/Debugger/Debugger.Script.md

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+# Debugger.Script
+A `Debugger.Script` instance refers to a sequence of bytecode in the
+debuggee; it is the [`Debugger`][debugger-object] API's presentation of a JSAPI `JSScript`
+object. Each of the following is represented by single JSScript object:
+* The body of a function—that is, all the code in the function that is not
+contained within some nested function.
+* The code passed to a single call to `eval`, excluding the bodies of any
+functions that code defines.
+* The contents of a `<script>` element.
+* A DOM event handler, whether embedded in HTML or attached to the element
+by other JavaScript code.
+* Code appearing in a `javascript:` URL.
+The [`Debugger`][debugger-object] interface constructs `Debugger.Script` objects as scripts
+of debuggee code are uncovered by the debugger: via the `onNewScript`
+handler method; via [`Debugger.Frame`][frame]'s `script` properties; via the
+`functionScript` method of [`Debugger.Object`][object] instances; and so on. For a
+given [`Debugger`][debugger-object] instance, SpiderMonkey constructs exactly one
+`Debugger.Script` instance for each underlying script object; debugger
+code can add its own properties to a script object and expect to find
+them later, use `==` to decide whether two expressions refer to the same
+script, and so on.
+(If more than one [`Debugger`][debugger-object] instance is debugging the same code, each
+[`Debugger`][debugger-object] gets a separate `Debugger.Script` instance for a given
+script. This allows the code using each [`Debugger`][debugger-object] instance to place
+whatever properties it likes on its `Debugger.Script` instances, without
+worrying about interfering with other debuggers.)
+A `Debugger.Script` instance is a strong reference to a JSScript object;
+it protects the script it refers to from being garbage collected.
+Note that SpiderMonkey may use the same `Debugger.Script` instances for
+equivalent functions or evaluated code—that is, scripts representing the
+same source code, at the same position in the same source file,
+evaluated in the same lexical environment.
+## Accessor Properties of the Debugger.Script Prototype Object
+A `Debugger.Script` instance inherits the following accessor properties
+from its prototype:
+`url`
+:   The filename or URL from which this script's code was loaded. If the
+`source` property is non-`null`, then this is equal to `source.url`.
+`startLine`
+:   The number of the line at which this script's code starts, within the
+file or document named by `url`.
+`lineCount`
+:   The number of lines this script's code occupies, within the file or
+document named by `url`.
+`source`
+:   The [`Debugger.Source`][source] instance representing the source code from which
+this script was produced. This is `null` if the source code was not
+retained.
+`sourceStart`
+:   The character within the [`Debugger.Source`][source] instance given by `source` at
+which this script's code starts; zero-based. If this is a function's
+script, this is the index of the start of the `function` token in the
+source code.
+`sourceLength`
+:   The length, in characters, of this script's code within the
+[`Debugger.Source`][source] instance given by `source`.
+`global`
+:   A [`Debugger.Object`][object] instance referring to the global object in whose
+scope this script runs. The result refers to the global directly, not
+via a wrapper or a `WindowProxy` ("outer window", in Firefox).
+`staticLevel`
+:   The number of function bodies enclosing this script's code.
+Global code is at level zero; bodies of functions defined at the top
+level in global code are at level one; bodies of functions nested within
+those are at level two; and so on.
+A script for code passed to direct `eval` is at a static level one
+greater than that of the script containing the call to `eval`, because
+direct eval code runs within the caller's scope. However, a script for
+code passed to an indirect `eval` call is at static level zero, since it
+is evaluated in the global scope.
+Note that a generator's expressions are considered to be part of the
+body of a synthetic function, produced by the compiler.
+Scripts' static level be useful in deciding where to set breakpoints.
+For example, a breakpoint set on line 3 in this code:
+function f() {
+x = function g() {  // line 2
+// line 3; no code here
+...;
+}
+}
+should be set in `g`'s script, not in `f`'s, even though neither script
+contains code at that line. In such a case, the most deeply nested
+script—the one with the highest static level—should receive the
+breakpoint.
+`strictMode`
+:   This is `true` if this script's code is ECMAScript strict mode code, and
+`false` otherwise.
+`sourceMapURL`
+:   If this script was produced by a minimizer or translated from some other
+language, and we know the URL of a <b>source map</b> document relating
+the source positions in this script to the corresponding source
+positions in the original source, then this property's value is that
+URL. Otherwise, this is `null`.
+(On the web, the translator may provide the source map URL in a
+specially formatted comment in the JavaScript source code, or via a
+header in the HTTP reply that carried the generated JavaScript.)
+## Function Properties of the Debugger.Script Prototype Object
+The functions described below may only be called with a `this` value
+referring to a `Debugger.Script` instance; they may not be used as
+methods of other kinds of objects.
+<code>decompile([<i>pretty</i>])</code>
+:   Return a string containing JavaScript source code equivalent to this
+script in its effect and result. If <i>pretty</i> is present and true,
+produce indented code with line breaks.
+(Note that [`Debugger.Object`][object] instances referring to functions also have
+a `decompile` method, whose result includes the function header and
+parameter names, so it is probably better to write
+<code><i>f</i>.decompile()</code> than to write
+<code><i>f</i>.getFunctionScript().decompile()</code>.)
+`getAllOffsets()`
+:   Return an array <i>L</i> describing the relationship between bytecode
+instruction offsets and source code positions in this script. <i>L</i>
+is sparse, and indexed by source line number. If a source line number
+<i>line</i> has no code, then <i>L</i> has no <i>line</i> property. If
+there is code for <i>line</i>, then <code><i>L</i>[<i>line</i>]</code> is an array
+of offsets of byte code instructions that are entry points to that line.
+For example, suppose we have a script for the following source code:
+a=[]
+for (i=1; i < 10; i++)
+// It's hip to be square.
+a[i] = i*i;
+Calling `getAllOffsets()` on that code might yield an array like this:
+[[0], [5, 20], , [10]]
+This array indicates that:
+* the first line's code starts at offset 0 in the script;
+* the `for` statement head has two entry points at offsets 5 and 20 (for
+the initialization, which is performed only once, and the loop test,
+which is performed at the start of each iteration);
+* the third line has no code;
+* and the fourth line begins at offset 10.
+<code>getLineOffsets(<i>line</i>)</code>
+:   Return an array of bytecode instruction offsets representing the entry
+points to source line <i>line</i>. If the script contains no executable
+code at that line, the array returned is empty.
+<code>getOffsetLine(<i>offset</i>)</code>
+:   Return the source code line responsible for the bytecode at
+<i>offset</i> in this script.
+`getChildScripts()`
+:   Return a new array whose elements are Debugger.Script objects for each
+function and each generator expression in this script. Only direct
+children are included; nested children can be reached by walking the
+tree.
+<code>setBreakpoint(<i>offset</i>, <i>handler</i>)</code>
+:   Set a breakpoint at the bytecode instruction at <i>offset</i> in this
+script, reporting hits to the `hit` method of <i>handler</i>. If
+<i>offset</i> is not a valid offset in this script, throw an error.
+When execution reaches the given instruction, SpiderMonkey calls the
+`hit<code> method of <i>handler</i>, passing a [</code>Debugger.Frame`][frame] instance
+representing the currently executing stack frame. The `hit` method's
+return value should be a [resumption value][rv], determining how execution should
+continue.
+Any number of breakpoints may be set at a single location; when control
+reaches that point, SpiderMonkey calls their handlers in an unspecified
+order.
+Any number of breakpoints may use the same <i>handler</i> object.
+Breakpoint handler method calls are cross-compartment, intra-thread
+calls: the call takes place in the same thread that hit the breakpoint,
+and in the compartment containing the handler function (typically the
+debugger's compartment).
+The new breakpoint belongs to the [`Debugger`][debugger-object] instance to which this
+script belongs; disabling the [`Debugger`][debugger-object] instance disables this
+breakpoint.
+<code>getBreakpoints([<i>offset</i>])</code>
+:   Return an array containing the handler objects for all the breakpoints
+set at <i>offset</i> in this script. If <i>offset</i> is omitted, return
+the handlers of all breakpoints set anywhere in this script. If
+<i>offset</i> is present, but not a valid offset in this script, throw
+an error.
+<code>clearBreakpoints(handler, [<i>offset</i>])</code>
+:   Remove all breakpoints set in this [`Debugger`][debugger-object] instance that use
+<i>handler</i> as their handler. If <i>offset</i> is given, remove only
+those breakpoints set at <i>offset</i> that use <i>handler</i>; if
+<i>offset</i> is not a valid offset in this script, throw an error.
+Note that, if breakpoints using other handler objects are set at the
+same location(s) as <i>handler</i>, they remain in place.
+<code>clearAllBreakpoints([<i>offset</i>])</code>
+:   Remove all breakpoints set in this script. If <i>offset</i> is present,
+remove all breakpoints set at that offset in this script; if
+<i>offset</i> is not a valid bytecode offset in this script, throw an
+error.

The Tor Browser / file comparison

comparison: js/src/doc/Debugger/Debugger.Script.md

js/src/doc/Debugger/Debugger.Script.md