searching values in array javascript

Is there a built-in function in javascript to do this or this is only the option to go? Please look at the code below:

var arr=[1,3,4,'+','-', or whatever]

function value_check(user_click){

  var operators=['+','-','/','*','.']
  for (var i=0;i    if (arr[arr.length-1]==operators[i]){var value1='operator found';}

    if (user_click==operators[i]){
     var value2= value1;alert("consecutive operators"); break;
    }
  }
}

I think this code achieves what I intend to do but is there a simple and shorter way of doing this. In words, I want to achieve something like this:

if (arr[arr.length-1] && user_click BOTH ARE IN operators array) 

  alert("consecutive operators)