Given a JSON Object, the task is to check whether a key exists in the Object or not using JavaScript. We’re going to discuss a few methods.
JavaScript hasOwnProperty() Method: This method returns a boolean denoting whether the object has the defined property as its own property (as opposed to inheriting it).
Syntax:
obj.hasOwnProperty(prop)
Parameters:
- prop: This parameter is required. It specifies the string name or Symbol of the property to check.
Return Value: It returns a boolean value indicating whether the object has the given property as its own property.
Example 1: This example checks for prop_1 of the obj by using hasOwnProperty property.
Javascript
let obj = {
prop_1: "val_1" ,
prop_2: "val_2" ,
prop_3: "val_3" ,
prop_4: "val_4" ,
};
function gfg_Run() {
ans = "" ;
let prop = 'prop_1' ;
if (obj.hasOwnProperty(prop)) {
ans = "let 'obj' has " + prop + " property" ;
} else {
ans = "let 'obj' has not " + prop + " property" ;
}
console.log(ans);
}
gfg_Run()
|
Outputlet 'obj' has prop_1 property
Example 2: This example checks for pro_1 of the obj by simple array access.
Javascript
let obj = {
prop_1: "val_1" ,
prop_2: "val_2" ,
prop_3: "val_3" ,
prop_4: "val_4" ,
};
function gfg_Run() {
ans = "" ;
let prop = 'pro_1' ;
if (obj[prop]) {
ans = "let 'obj' has " + prop + " property" ;
} else {
ans = "let 'obj' has not " + prop + " property" ;
}
console.log(ans);
}
gfg_Run()
|
Outputlet 'obj' has not pro_1 property