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<p><strong><code>parseFloat()</code> </strong>函数解析一个字符串参数并返回一个浮点数。</p>
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<div><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/globalprops-parsefloat.html" width="100%"></iframe></div>
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<h2 id="语法">语法</h2>
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<pre class="syntaxbox">parseFloat(<em>value</em>)</pre>
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<pre><code class="language-javascript">parseFloat(<em>value</em>)</code></pre>
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<h3 id="参数">参数</h3>
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<dl>
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<dt><code>value</code></dt>
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<h2 id="例子">例子</h2>
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<h3 id="例子_parseFloat返回正常数字">例子: <code>parseFloat</code>返回正常数字</h3>
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<p>下面的例子都返回<strong>3.14</strong></p>
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<pre class="brush:js">parseFloat("3.14");
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<pre><code class="language-js">parseFloat("3.14");
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parseFloat("314e-2");
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parseFloat("0.0314E+2");
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parseFloat("3.14more non-digit characters");
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</pre>
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</code></pre>
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<h3 id="例子_parseFloat返回NaN">例子: <code>parseFloat</code>返回NaN</h3>
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<p>下面的例子将返回<code>NaN</code></p>
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<pre class="brush: js">parseFloat("FF2");
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</pre>
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<pre><code class="language-javascript">parseFloat("FF2");
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</code></pre>
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<h3 id="更严格的转换函数">更严格的转换函数</h3>
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<p>该函数通过正则表达式的方式,在需要更严格地转换float值时可能会有用:</p>
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<pre class="brush: js">var filterFloat = function (value) {
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<pre><code class="language-javascript">var filterFloat = function (value) {
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if(/^(\-|\+)?|(\.\d+)(\d+(\.\d+)?|(\d+\.)|Infinity)$/
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.test(value))
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return Number(value);
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@@ -56,7 +56,7 @@ console.log(filterFloat('421hop')); // NaN
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console.log(filterFloat('hop1.61803398875')); // NaN
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console.log(filterFloat("999 888")); // NaN
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console.log(filterFloat('.421')); // 0.421
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console.log(filterFloat('421.')); // 421</pre>
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console.log(filterFloat('421.')); // 421</code></pre>
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<p>注意上面的代码只是示例。</p>
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<h2 id="规范">规范</h2>
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<table class="standard-table">
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