js check class code example

Example 1: javascript check if element has class

if(document.getElementById("myElmentID").classList.contains("hidden")){
// I have the 'hidden' class
}

Example 2: js check for class in classList

element.classList.contains(className);

Example 3: instance of

The instanceof keyword checks whether an object
is an instance of a specific class or an interface.
The instanceof keyword compares the
instance with type. The return value
is either true or false .

Example 4: check if has name javascript

function whatIsInAName(collection, source) {
  // "What's in a name? that which we call a rose
  // By any other name would smell as sweet.”
  // -- by William Shakespeare, Romeo and Juliet
  var srcKeys = Object.keys(source);

  return collection.filter(function(obj) {
    return srcKeys.every(function(key) {
      return obj.hasOwnProperty(key) && obj[key] === source[key];
    });
  });
}

// test here
whatIsInAName(
  [
    { first: "Romeo", last: "Montague" },
    { first: "Mercutio", last: null },
    { first: "Tybalt", last: "Capulet" }
  ],
  { last: "Capulet" }
);