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authorPeter Bengtsson <mail@peterbe.com>2020-12-08 14:40:17 -0500
committerPeter Bengtsson <mail@peterbe.com>2020-12-08 14:40:17 -0500
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+---
+title: 'TypeError: "x" is not a non-null object'
+slug: Web/JavaScript/Reference/Errors/No_non-null_object
+tags:
+ - JavaScript
+ - 类型错误
+ - 错误提示
+translation_of: Web/JavaScript/Reference/Errors/No_non-null_object
+---
+<div>{{JSSidebar("Errors")}}</div>
+
+<h2 id="提示信息">提示信息</h2>
+
+<pre class="syntaxbox">TypeError: "x" is not a non-null object (Firefox)
+TypeError: Property description must be an object: "x" (Chrome)
+TypeError: Invalid value used in weak set (Chrome)
+</pre>
+
+<h2 id="错误类型">错误类型</h2>
+
+<p>{{jsxref("TypeError")}}</p>
+
+<h2 id="哪里出错了?">哪里出错了?</h2>
+
+<p>在期待出现对象类型的值的地方而没有提供。{{jsxref("null")}} 不是对象类型,因此不起作用。必须在给定的场景下提供一个合适的对象。</p>
+
+<h2 id="示例">示例</h2>
+
+<h3 id="期望的属性描述器">期望的属性描述器</h3>
+
+<p>当使用诸如 {{jsxref("Object.create()")}} 或 {{jsxref("Object.defineProperty()")}} 及{jsxref("Object.defineProperties()")}} 方法时,可选的属性描述器参数需要提供一个描述器对象。提供非对象类型的值(例如数字)将会报错:</p>
+
+<pre class="brush: js example-bad">Object.defineProperty({}, 'key', 1);
+// TypeError: 1 is not a non-null object
+
+Object.defineProperty({}, 'key', null);
+// TypeError: null is not a non-null object
+</pre>
+
+<p>一个合法的描述器对象类似于下面这样:</p>
+
+<pre class="brush: js example-good">Object.defineProperty({}, 'key', { value: 'foo', writable: false });
+</pre>
+
+<h3 id="WeakMap_和_WeakSet_对象需要对象类型的键"><code>WeakMap</code> 和 <code>WeakSet</code> 对象需要对象类型的键</h3>
+
+<p>{{jsxref("WeakMap")}} 和 {{jsxref("WeakSet")}} 对象只能存储对象类型的键,而不能使用其他类型的。</p>
+
+<pre class="brush: js example-bad">var ws = new WeakSet();
+ws.add('foo');
+// TypeError: "foo" is not a non-null object</pre>
+
+<p>用对象类型的值来替换:</p>
+
+<pre class="brush: js example-good">ws.add({foo: 'bar'});
+ws.add(window);
+</pre>
+
+<h2 id="相关内容">相关内容</h2>
+
+<ul>
+ <li>{{jsxref("Object.create()")}}</li>
+ <li>{{jsxref("Object.defineProperty()")}}, {{jsxref("Object.defineProperties()")}}</li>
+ <li>{{jsxref("WeakMap")}}, {{jsxref("WeakSet")}}</li>
+</ul>