​x
 
<!DOCTYPE html>
<html>
<body>
​
<h2>JavaScript 数字</h2>
​
<p>toExponential() 方法将数字转换为指数计数法：</p>
​
<p id="demo"></p>
​
<script>
let num = 5.56789;
let n = num.toExponential(3);
document.getElementById("demo").innerHTML = n;
</script>
​
</body>
</html>
​