js object set property code example

Example 1: js defineProperty

// using __proto__
var obj = {};
var descriptor = Object.create(null); // no inherited properties
descriptor.value = 'static';

// not enumerable, not configurable, not writable as defaults
Object.defineProperty(obj, 'key', descriptor);

// being explicit
Object.defineProperty(obj, 'key', {
  enumerable: false,
  configurable: false,
  writable: false,
  value: 'static'
});

// recycling same object
function withValue(value) {
  var d = withValue.d || (
    withValue.d = {
      enumerable: false,
      writable: false,
      configurable: false,
      value: value
    }
  );

  // avoiding duplicate operation for assigning value
  if (d.value !== value) d.value = value;

  return d;
}
// ... and ...
Object.defineProperty(obj, 'key', withValue('static'));

// if freeze is available, prevents adding or
// removing the object prototype properties
// (value, get, set, enumerable, writable, configurable)
(Object.freeze || Object)(Object.prototype);

Example 2: 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 3: add property with value in js

var myObject = {
    sProp: 'some string value',
    numProp: 2,
    bProp: false
};