freeCodeCamp/guide/english/certifications/javascript-algorithms-and-data-structures/object-oriented-programming/use-closure-to-protect-properties-within-an-object-from-being-modified-externally/index.md

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Use Closure to Protect Properties Within an Object from Being Modified Externally

Use Closure to Protect Properties Within an Object from Being Modified Externally

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Problem Explanation

Just like in the example given, rather than declaring the weight variable with the this keyword, the let keyword must be used to declare it as a private variable. This way it can only be accessed inside the Bird function. The getWeight method must then be added inside the Bird function to access the weight variable.

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Solutions

Solution 1 (Click to Show/Hide)

function Bird() {
  let weight = 15;

  this.getWeight = function() {
    return weight;
  };
}

Solution 1 (Click to Show/Hide)

In ES6 syntax we can make the function a bit less verbose:

function Bird() {
  let weight = 15;
  this.getWeight = () => weight;  
}