Prevent Object Mutation

This shows how you can lock an object so its content cannot be modified. if you comment out the line Object.freeze(my_object); it will allow it to be modified again.

JS

function run_function() {
  let my_object = {
    i: "am awesome",
  }
  Object.freeze(my_object);
  my_object.i = "am still awesome"; // this should not change the object as its frozen
  write_result(my_object);
  console.log(my_object);
  return my_object;
}

// this is a common function just to write the content into the result div
function write_result(result) {
  var result_html = document.getElementById("result");
  result_html.innerHTML = result;
}

HTML

<div id='result' class='mb-3 alert alert-primary'>..</div>
<button onclick='run_function();' class='btn btn-primary mb-1'>Run Function</button>

Working Result

Test Result Below

..

Posted in javascript

11:16 pm, September 30, 2019

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