title: Javascript findIndex is not a function
body: <p>I have a json array:</p>
  
  <pre><code>[    
    {"id":19,"name":"Jed", "lastname":"DIAZ", "hobby":"photo", "birthday":"2011/11/22"},
    {"id":20,"name":"Judith", "lastname":"HENDERSON", "hobby":"pets", "birthday":"1974/06/12"},
    {"id":21,"name":"Nicolai", "lastname":"GRAHAM", "hobby":"reading", "birthday":"2005/01/22"},
    {"id":22,"name":"Vasile", "lastname":"BRYANT", "hobby":"singing", "birthday":"1987/03/17"}
  ]
  </code></pre>
  
  <p>function to remove a item from json array</p>
  
  <pre><code> removeItem: function(removeId){
     //paramater validation
     return dataLoad.then(function(data){
  
       f = data.findIndex(function(item) { return item.id == removeId; });
  
       if(f &lt; 0)
         return false;
       data.splice(f,1);
  
       LS.setData(data,"cutomers");
  
       return true;
     });
   }
  </code></pre>
  
  <p>When the code is running there is an error:</p>
  
  <blockquote>
    <p>findIndex is not a function</p>
  </blockquote>
  
  <p>error line</p>
  
  <pre><code> f = data.findIndex(function(item) { return item.id == removeId; });
  </code></pre>