var bmi = weight / (height**2); if (isNaN(bmi)) { console.log("请正确输入数值") } else if (bmi < 18.5) { console.log("过轻"); } else if (bmi < 25 ) { console.log("正常"); } else if (bmi < 28 ) { console.log("过重"); } else if (bmi < 32 ) { console.log("肥胖"); } else { console.log("严重肥胖"); }