---
title: Error.prototype.toString()
slug: Web/JavaScript/Reference/Global_Objects/Error/toString
translation_of: Web/JavaScript/Reference/Global_Objects/Error/toString
---
<div>
 {{JSRef("Global_Objects", "Error", "EvalError,InternalError,RangeError,ReferenceError,SyntaxError,TypeError,URIError")}}</div>
<h2 id="Summary">概述</h2>
<p><code><strong>toString()</strong></code> 方法返回一个指定的错误对象（Error object）的字符串表示。</p>
<h2 id="Syntax">语法</h2>
<pre class="syntaxbox"><code><em>e</em>.toString();</code></pre>
<h2 id="Description">描述</h2>
<p>{{jsxref("Error")}} 对象覆盖了 {{jsxref("Object.prototype.toString()")}} 方法。该方法实现如下：（假定 <code>Object</code> 和 <code>String</code> 没有被更改）：</p>
<pre class="brush:js">Error.prototype.toString = function()
{
  "use strict";

  var obj = Object(this);
  if (obj !== this)
    throw new TypeError();

  var name = this.name;
  name = (name === undefined) ? "Error" : String(name);

  var msg = this.message;
  msg = (msg === undefined) ? "" : String(msg);

  if (name === "")
    return msg;
  if (msg === "")
    return name;

  return name + ": " + msg;
};
</pre>
<h2 id="Example">示例</h2>
<pre class="brush:js">var e = new Error("fatal error");
print(e.toString()); // "Error: fatal error"

e.name = undefined;
print(e.toString()); // "Error: fatal error"

e.name = "";
print(e.toString()); // "fatal error"

e.message = undefined;
print(e.toString()); // "Error"

e.name = "hello";
print(e.toString()); // "hello"
</pre>

<h2 id="规范">规范</h2>

{{Specifications}}

<h2 id="浏览器兼容性">浏览器兼容性</h2>

{{Compat}}

<h2 id="See_also">相关链接</h2>
<ul>
 <li>{{jsxref("Error.prototype.toSource()")}}</li>
</ul>