代码示例:(标识:js_number_toexponential)
<!DOCTYPE html>
<html>
<body>

<h2>JavaScript Number 方法</h2>

<p>toExponential() 返回字符串,其中的数字四舍五入并使用指数表示法书写。</p>

<p>可选参数定义小数点后的位数。</p>

<p id="demo"></p>

<script>
let x = 9.656;
document.getElementById("demo").innerHTML =
  x.toExponential() + "<br>" + 
  x.toExponential(2) + "<br>" + 
  x.toExponential(4) + "<br>" + 
  x.toExponential(6);
</script>

</body>
</html>
运行结果: