how to find out if a key exists in an object javascript code example
Example 1: javascript does key exist
var person={"name":"Billy","age":20}
person.hasOwnProperty("name");
person.hasOwnProperty("sex");
Example 2: javascript check if key exists in object
"key" in obj
If you want to check if a key doesn't exist, remember to use parenthesis:
!("key" in obj)
!"key" in obj
Or, if you want to particularly test for properties of the object instance (and not inherited properties), use hasOwnProperty:
obj.hasOwnProperty("key")