代码示例：（标识：jsck_issafeinteger_1）
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript 数字</h1>
<h2>Number.isSafeInteger() 方法</h2>
<p>如果值是安全整数且数据类型为 Number，则 Number.isSafeInteger() 返回 true：</p>
<p id="demo"></p>
<p>Internet Explorer 11 或更早版本不支持 Number.isSafeInteger()。</p>
<script>
let result =
"Is 123 a safe integer? " + Number.isSafeInteger(123) + "<br>" +
"Is +123 a safe integer? " + Number.isSafeInteger(-123) + "<br>" +
"Is '123' a safe integer? " + Number.isSafeInteger('123');
document.getElementById("demo").innerHTML = result;
</script>
</body>
</html>
