js add property to object code example

Example 1: add property to string js

const s = 'Hello world!'
  s.user = 'Jack';     // no error if used without 'use-strict'

  console.log(s.user); // undefined

Example 2: how to add property to object in javascript

var data = {
    'PropertyA': 1,
    'PropertyB': 2,
    'PropertyC': 3
};

data["PropertyD"] = 4;

// dialog box with 4 in it
alert(data.PropertyD);
alert(data["PropertyD"]);

Example 3: ad data to js object

//Consider the following example object literal:
var myObject = {
    sProp: 'some string value',
    numProp: 2,
    bProp: false
};

//You can use dot syntax to add a new property to it as follows:
myObject.prop2 = 'data here';

//Modify a Property of an Object Literal
//The process for modifying a property is essentially the same. 
//Here we will assign a new value to the sProp property shown in the 
//original myObject definition above:
myObject.sProp = 'A new string value for our original string property';

//Read Current Value of Object Property
//The following demonstrates how to access a property of an object literal:
alert(myObject.sProp) // display myObject.sProp value in alert
var val = myObject.sProp; // assign myObject.sProp to variable

Example 4: add property to object javascript

let yourObject = {};

//Examples:
//Example 1
let yourKeyVariable = "yourKey";
yourObject[yourKeyVariable] = "yourValue";

//Example 2
yourObject["yourKey"] = "yourValue";

//Example 3
yourObject.yourKey = "yourValue";

Example 5: how to a property from a JavaScript object

delete myObject.regex;
// or,
delete myObject['regex'];
// or,
var prop = "regex";
delete myObject[prop];


/** Demo */
var myObject = {
    "ircEvent": "PRIVMSG",
    "method": "newURI",
    "regex": "^http://.*"
};
delete myObject.regex;

console.log(myObject);

Example 6: Add New Properties to a JavaScript Object

var myDog = {
  "name": "Happy Coder",
  "legs": 4,
  "tails": 1,
  "friends": ["freeCodeCamp Campers"]
};

myDog.bark = "woof";
// or
myDog["bark"] = "woof";