cssAudio - Activefile-genericCSS - ActiveGeneric - ActiveHTML - ActiveImage - ActiveJS - ActiveSVG - ActiveText - Activefile-genericVideo - ActiveLovehtmlicon-new-collectionicon-personicon-teamlog-outoctocatpop-outspinnerstartv

Pen Settings

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

Quick-add: + add another resource

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

Quick-add: + add another resource

Code Indentation

     

Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

            
              // Create a defensive factory
const defensiveObjectFactory = (obj) => {

  // Our handler that rejects any change to the object and any nested objects inside it
  const rejector = {
    get(obj, prop) {

      // If dealing with nested object, nest the proxy untill it reaches the direct property of it's parent proxy
      if (typeof obj[prop] === 'object' && obj[prop] !== null) return new Proxy(obj[prop], rejector)
      
      // If prop is directly accessible, just do the default operation
      else return obj[prop]

    },

    set(obj, prop, val, rec) {

      // This time we traverse the object tree to see whether it contains prop or not
      
      // If prop is not currently present in obj, add it
      if (!(prop in obj)) {
        obj[prop] = val
        return true
      }

      // Else warn about it and prevent assignment
      console.warn(`Can not set prop ${prop} on freezed object`)
      
      // Return the proxy itself.
      // Note that we could return false, since returning false will create a TypeError, the latter code would always have to be inside a try-catch block which is immpossible and not flexbile.
      return rec
      
    }
  }
}

// Now let's use it and put it into test
// Start our object with default values
let testObj = freezeObjectFactory({name: 'Farzad', parent: {father: {name: 'Ali'}}})

// try to change values
testObj.name = 'John' // Can not set prop name on freezed object

testObj.parent.father.name = 'Mark' // Can not set prop name on freezed object

testObj.id = 1 // In this case it could be added cause id is new

console.log(testObj) // not the same object, it has `id` on it
            
          
!
999px
Loading ..................

Console