check all properties of object javascript code example

Example 1: check the properties of an object in javascript

for (var name in object) {  
    if (object.hasOwnProperty(name)) { 
        // do something with name                    
    }  
}

// OR

const hero = {
  name: 'Batman'
};

hero.hasOwnProperty('name');     // => true
hero.hasOwnProperty('realName'); // => false

Example 2: javascript access property values list of objects

// Access all properties and values in a JS object:
let valuesArray = Object.entries(MyObject);
  
   for (let value of valuesArray) { 
       document.write(value + "<br>"); // value is the property,value pair
   } 
/* Result: propName,value
           propName,value
 		   ...

For clarity: */
let person = {
  name: "Piet",
  age: 42
};

Object.keys(person) // = ["name", "age"]
Object.values(person) // = ["Piet", 42]
Object.entries(person) // = [ ["name","Piet"], ["age",42] ]

Example 3: 3 dots to get all object properties in JS

this.setState(prevState => {
    return {foo: {...prevState.foo, a: "updated"}};
});