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---
title: 'SyntaxError: "use strict" not allowed in function with non-simple parameters'
slug: Web/JavaScript/Reference/Errors/Strict_Non_Simple_Params
tags:
- Errors
- JavaScript
- SyntaxError
- TypeError
- use strict
translation_of: Web/JavaScript/Reference/Errors/Strict_Non_Simple_Params
---
<div>{{jsSidebar("Errors")}}</div>
<h2 id="信息">信息</h2>
<pre class="syntaxbox">Firefox:
句法错误: "use strict" 不允许在带默认参数的函数中
句法错误: "use strict" 不允许在带rest参数的函数中
句法错误: "use strict" 不允许在带解构参数的函数中
Chrome:
句法错误: 非法的'use strict'指令,在带有非简单参数列表的函数中
</pre>
<h2 id="错误类型">错误类型</h2>
<p>{{jsxref("SyntaxError")}}.</p>
<h2 id="哪里出错了">哪里出错了?</h2>
<p>在函数顶部直接写了 <code>"use strict"</code> ，而该函数拥有以下的参数其中之一：</p>
<ul>
<li>{{jsxref("Functions/Default_parameters", "默认参数", "", 1)}}</li>
<li>{{jsxref("Functions/rest_parameters", "剩余参数", "", 1)}}</li>
<li>{{jsxref("Operators/Destructuring_assignment", "解构赋值", "", 1)}}</li>
</ul>
<p>根据ECMAScript规范，不允许在这些函数的顶部使用“use strict”指令。</p>
<h2 id="示例">示例</h2>
<h3 id="函数语句">函数语句</h3>
<p>在这种情况下，函数sum具有默认参数a = 1和b = 2：</p>
<pre class="brush: js example-bad">function sum(a=1, b=2) {
// SyntaxError: "use strict" not allowed in function with default parameter
"use strict";
return a + b;
}
</pre>
<p>如果这个函数应该处于 <a href="/en-US/docs/Web/JavaScript/Reference/Strict_mode">strict mode</a>，并且整个脚本或封装函数也可以在严格模式下，可以移动 "use strict" 指令到函数之外:</p>
<pre class="brush: js example-good">"use strict";
function sum(a=1, b=2) {
return a + b;
}
</pre>
<h3 id="函数表达式">函数表达式</h3>
<p>函数表达式可以使用另一种解决方法：</p>
<pre class="brush: js example-bad">var sum = function sum([a, b]) {
// SyntaxError: "use strict" not allowed in function with destructuring parameter
"use strict";
return a + b;
};
</pre>
<p>这可以转换为以下表达式：</p>
<pre class="brush: js example-good">var sum = (function() {
"use strict";
return function sum([a, b]) {
return a + b;
};
})();
</pre>
<h3 id="箭头函数">箭头函数</h3>
<p>如果箭头函数需要访问 <code>this</code>，则可以将箭头函数作为封闭函数来使用:</p>
<pre class="brush: js example-bad">var callback = (...args) => {
// SyntaxError: "use strict" not allowed in function with rest parameter
"use strict";
return this.run(args);
};
</pre>
<p>这可以转换为以下表达式：</p>
<pre class="brush: js example-good">var callback = (() => {
"use strict";
return (...args) => {
return this.run(args);
};
})();
</pre>
<h2 id="也可以看看">也可以看看</h2>
<ul>
<li>{{jsxref("Strict_mode", "Strict mode", "", 1)}}</li>
<li>{{jsxref("Statements/function", "函数语句", "", 1)}}</li>
<li>{{jsxref("Operators/function", "函数表达式", "", 1)}}</li>
<li>{{jsxref("Functions/Default_parameters", "默认参数", "", 1)}}</li>
<li>{{jsxref("Functions/rest_parameters", "剩余参数", "", 1)}}</li>
<li>{{jsxref("Operators/Destructuring_assignment", "解构参数", "", 1)}}</li>
</ul>
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