我用Javascript创建了这个简单的应用程序,但我不断收到一个错误,说“Uncaught TypeError: Cannot read property 'value' of null
”,这发生在行“var age = document.getElementById("age").value;
”我一直在寻找问题的每个地方,但我只是没有看到它。请查看我的代码并帮助我。谢谢!JavaScript空值错误
<script>
function calculateBMR()
{
var gender = document.getElementById("gender").value;
var age = document.getElementById("age").value;
var weigth = document.getElementById("weight").value;
var heigth = document.getElementById("height").value;
console.log(gender);
if (gender == "male")
{
var result = 66 + (6.23 * weight) + (12.7 * height) - (6.8 *age);
}
else if (gender == "female")
{
var result = 655 + (4.35 * weight) + (4.7 * height) - (4.7 * age);
}
document.bmrForm.bmr.value = result;
};
</script>
<form name = "bmrForm">
Gender:
<br />
<select id="gender">
<option value="male">male</option>
<option value="female">female</option>
</select>
<br />
Age:
<br />
<input type = "text" name ="age" size = "10">
<br />
Weigth (lb.) :
<br />
<input type = "text" name ="weight" size = "10">
<br />
Heigth (inches) :
<br />
<input type = "text" name = "height" size = "10">
<br />
<br />
<input type = "button" value = "Calculate BMR" onClick = "calculateBMR();">
<br />
<br />
BMR:
<br />
<input type = "text" name = "bmr">
</form>
ID不是网页上找到'age','weight','height' – Tushar