javascript - Check that the array is unique

var thelist = new Array();
function addlist(){
thelist.push(documentgetElementById('data').innerHTML);

}

How can I check that the data I push does not already exsist in array thelist?

Answer

var thelist = []; // Use the array literal, not the constructor.
function addlist(){

  // get the data we want to make sure is unique
  var data = documentgetElementById('data').innerHTML;


  // make a flag to keep track of whether or not it exists.
  var exists = false;

  // Loop through the array
  for (var i = 0; i < thelist.length; i++) {

    // if we found the data in there already, flip the flag
    if (thelist[i] === data) {
      exists = true;


      // stop looping, once we have found something, no reason to loop more.
      break;
    }
  }

  // If the data doesn't exist yet, push it on there.
  if (!exists) {
    thelist.push(data);
  }

}