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75 lines
3.0 KiB
75 lines
3.0 KiB
name: duk_del_prop
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proto: |
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duk_bool_t duk_del_prop(duk_context *ctx, duk_idx_t obj_idx);
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stack: |
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[ ... obj! ... key! ] -> [ ... obj! ... ]
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summary: |
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<p>Delete the property <code>key</code> of a value at <code>obj_idx</code>.
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<code>key</code> is removed from the stack. Return code and error throwing
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behavior:</p>
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<ul>
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<li>If property exists and is configurable (deletable), deletes the
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property and returns <code>1</code>.</li>
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<li>If property exists but is not configurable, throws an error
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(strict mode semantics).</li>
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<li>If property does not exist, returns <code>1</code> (<i>not</i> 0).</li>
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<li>If the value at <code>obj_idx</code> is not
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<a href="http://www.ecma-international.org/ecma-262/5.1/#sec-9.10">object coercible</a>,
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throws an error.</li>
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<li>If <code>obj_idx</code> is invalid, throws an error.</li>
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</ul>
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<p>The property deletion is equivalent to the ECMAScript expression
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<code>res = delete obj[key]</code>. For precise semantics, see
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<a href="http://www.ecma-international.org/ecma-262/5.1/#sec-11.2.1">Property Accessors</a>,
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<a href="http://www.ecma-international.org/ecma-262/5.1/#sec-11.4.1">The delete operator</a>
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and <a href="http://www.ecma-international.org/ecma-262/5.1/#sec-8.12.7">[[Delete]] (P, Throw)</a>.
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The return value and error throwing behavior mirrors the ECMAScript
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<code>delete</code> operator behavior.
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Both the target value and the <code>key</code> are coerced:</p>
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<ul>
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<li>The target value is automatically coerced to an object. However, this
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object is a temporary one, so deleting its properties is not very useful.</li>
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<li>The <code>key</code> argument is internally coerced using ToPropertyKey()
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coercion which results in a string or a Symbol. There is an internal
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fast path for arrays and numeric indices which avoids an explicit string
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coercion, so use a numeric <code>key</code> when applicable.</li>
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</ul>
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<p>If the target is a Proxy object which implements the <code>deleteProperty</code>
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trap, the trap is invoked and the API call return value matches the trap return value.</p>
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<div class="note">
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This API call returns <code>1</code> when the target property does not exist.
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This is not very intuitive, but follows ECMAScript semantics:
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<code>delete obj.nonexistent</code> also evaluates to <code>true</code>.
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</div>
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<p>If the key is a fixed string you can avoid one API call and use the
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<code><a href="#duk_del_prop_string">duk_del_prop_string()</a></code> variant.
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Similarly, if the key is an array index, you can use the
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<code><a href="#duk_del_prop_index">duk_del_prop_index()</a></code> variant.</p>
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<div include="object-can-be-any-value.html" />
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example: |
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duk_bool_t rc;
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duk_push_string(ctx, "myProperty");
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rc = duk_del_prop(ctx, -3);
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printf("delete obj.myProperty -> rc=%d\n", (int) rc);
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tags:
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- property
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seealso:
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- duk_del_prop_index
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- duk_del_prop_string
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- duk_del_prop_lstring
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- duk_del_prop_literal
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- duk_del_prop_heapptr
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introduced: 1.0.0
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