how to check if key exists in 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 hashtable contains key
if (obj.hasOwnProperty("key1")) {
...
}
Example 3: how to check if a key exists in an object javascript
!("key" in obj)
!"key" in obj
Example 4: check if a key exists in an object javascript
"key" in obj
Example 5: js check if object key exists
var obj = { key: undefined };
obj["key"] !== undefined