To determine whether the input is null get the JS code for the input type
- 2020-03-26 21:40:47
- OfStack
Use the typeof algorithm
Typeof has an undefined operand and returns "undefined".
Here, x is defined as the operand:
There are five cases;
Typeof (x) returns "number";
Typeof (x) returns "string";
Typeof (x) returns a Boolean;
Object, array, null&sponge; When: typeof(x) returns "object";
The function typeof(x) returns "function".
Such as:
<script type="text/javascript">
var x=123456;
alert( typeof(x));//The pop-up "number".
</script>