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99 lines
3.4 KiB
99 lines
3.4 KiB
name: duk_enum
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proto: |
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void duk_enum(duk_context *ctx, duk_idx_t obj_idx, duk_uint_t enum_flags);
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stack: |
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[ ... obj! ... ] -> [ ... obj! ... enum! ]
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summary: |
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<p>Create an enumerator for object at <code>obj_idx</code>. Enumeration
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details can be controlled with <code>enum_flags</code>. If the target value
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is not an object, throws an error.</p>
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<p>Enumeration flags:</p>
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<table>
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<tr>
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<td>DUK_ENUM_INCLUDE_NONENUMERABLE</td>
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<td>Enumerate also non-enumerable properties, by default only enumerable
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properties are enumerated.</td>
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</tr>
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<tr>
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<td>DUK_ENUM_INCLUDE_HIDDEN</td>
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<td>Enumerate also hidden Symbols, by default hidden Symbols are not
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enumerated. Use together with <code>DUK_ENUM_INCLUDE_SYMBOLS</code>.
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In Duktape 1.x this flag was called <code>DUK_ENUM_INCLUDE_INTERNAL</code>.</td>
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</tr>
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<tr>
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<td>DUK_ENUM_INCLUDE_SYMBOLS</td>
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<td>Include Symbols in the enumeration result. Hidden Symbols are not
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included unless <code>DUK_ENUM_INCLUDE_HIDDEN</code> is specified.</td>
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</tr>
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<tr>
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<td>DUK_ENUM_EXCLUDE_STRINGS</td>
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<td>Exclude strings from the enumeration result. By default strings are
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included.</td>
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</tr>
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<tr>
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<td>DUK_ENUM_OWN_PROPERTIES_ONLY</td>
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<td>Enumerate only an object's "own" properties, by default also inherited
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properties are enumerated.</td>
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</tr>
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<tr>
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<td>DUK_ENUM_ARRAY_INDICES_ONLY</td>
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<td>Enumerate only array indices, i.e. property names of the form "0", "1",
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"2", etc.</td>
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</tr>
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<tr>
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<td>DUK_ENUM_SORT_ARRAY_INDICES</td>
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<td>Apply the ES2015 [[OwnPropertyKeys]] enumeration order over the whole
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enumeration result rather than per inheritance level, this has the
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effect of sorting array indices (even when inherited). Also symbols
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are sorted after ordinary string keys (both in insertion order).</td>
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</tr>
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<tr>
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<td>DUK_ENUM_NO_PROXY_BEHAVIOR</td>
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<td>Enumerate a Proxy object itself without invoking Proxy behaviors.</td>
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</tr>
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</table>
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<p>Without any flags the enumeration behaves like <code>for-in</code>:
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own and inherited enumerable properties are included, and enumeration
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order follows the
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<a href="http://www.ecma-international.org/ecma-262/6.0/#sec-ordinary-object-internal-methods-and-internal-slots-ownpropertykeys">ECMAScript ES2015 [[OwnPropertyKeys]]</a>
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enumeration order, applied for each inheritance level.</p>
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<p>Once the enumerator has been created, use
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<code><a href="#duk_next">duk_next()</a></code> to extract keys (or key/value
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pairs) from the enumerator.</p>
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<div class="note">
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The ES2015 [[OwnPropertyKeys]] enumeration order is:
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(1) array indices in ascending order, (2) non-array-index keys in their
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insertion order, and (3) symbols in their insertion order. This rule
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is applied separately for each inheritance level, so that if array index
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keys are inherited, they will appear out-of-order in the result. For
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most practical code this is not an issue because array indices are very
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rarely inherited. You can force the whole enumeration sequence to be
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sorted using <code>DUK_ENUM_SORT_ARRAY_INDICES</code>.
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</div>
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example: |
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duk_enum(ctx, -3, DUK_ENUM_INCLUDE_NONENUMERABLE);
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while (duk_next(ctx, -1 /*enum_idx*/, 0 /*get_value*/)) {
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/* [ ... enum key ] */
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printf("-> key %s\n", duk_get_string(ctx, -1));
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duk_pop(ctx); /* pop_key */
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}
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duk_pop(ctx); /* pop enum object */
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tags:
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- object
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- property
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seealso:
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- duk_next
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introduced: 1.0.0
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