113 lines
2.7 KiB
Markdown
113 lines
2.7 KiB
Markdown
---
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title: 身体质量指数
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categories:
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- 作品
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- 工具
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keywords:
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- 健康
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tags:
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- JavaScript
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date: 2022-09-02 17:12:35
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mathjax: true
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---
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身体质量指数（Body Mass Index，简称BMI），简称体质指数，是由一个人的质量（体重）和身高计算出的一个数值。BMI的定义是体重除以身高的平方，以千克/平方米为单位表示，由质量（千克）和身高（米）得出：
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$$ BMI = { 体重 \over 身高 ^ {2} } $$
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身体质量指数是国际上衡量人体胖瘦程度以及是否健康的一个常用指标，BMI正常值在20至25之间，超过25为超重，30以上则属肥胖。
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## 计算器
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<style>
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#calculator,
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#calculator * {
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margin: 10px auto;
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box-sizing: border-box;
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}
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#calculator,
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#calculator button {
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width: 300px;
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}
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#calculator label,
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#calculator input {
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width: 150px;
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color: black;
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display: inline-block;
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}
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button {
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cursor: pointer;
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}
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</style>
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<div id="calculator">
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<div><label for="weight">体重（千克）：</label><input id="weight" type="text" autocomplete="off"></div>
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<div><label for="weight">身高（厘米）：</label><input id="height" type="text" autocomplete="off"></div>
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<div><label>您的BMI：</label><input id="bmi" type="text" disabled></div>
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<button onclick="calculate()">计算</button>
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</div>
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<script>
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bmi.value = 0
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function calculate() {
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const w = Number(weight.value)
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const h = Number(height.value) / 100
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bmi.value = (isNaN(w) || isNaN(h) || !h) ? 0 : (Math.round(w / h ** 2)).toFixed(1)
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}
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</script>
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<!-- more -->
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## 源码
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``` html
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<style>
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#calculator,
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#calculator * {
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margin: 10px auto;
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box-sizing: border-box;
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}
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#calculator,
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#calculator button { width: 300px; }
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button { cursor: pointer; }
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#calculator label,
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#calculator input {
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width: 150px;
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color: black;
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display: inline-block;
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}
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</style>
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<div id="calculator">
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<div>
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<label for="weight">体重（千克）：</label>
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<input id="weight" type="text" autocomplete="off">
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</div>
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<div>
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<label for="weight">身高（厘米）：</label>
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<input id="height" type="text" autocomplete="off">
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</div>
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<div>
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<label>您的BMI：</label>
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<input id="bmi" type="text" disabled>
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</div>
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<button onclick="calculate()">计算</button>
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</div>
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<script>
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bmi.value = 0
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function calculate() {
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const w = Number(weight.value)
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const h = Number(height.value) / 100
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bmi.value = (isNaN(w) || isNaN(h) || !h) ? 0 : (Math.round(w / h ** 2)).toFixed(1)
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}
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</script>
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```
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