How to use array.push on array with a defined index?

How do I use array.push to add an object with a custom index in an array?

I have this script but it doesnt work. Chrome's Javascript console is not outputting errors

var tempList = new Array();
$('#add').click(function(){
  var split = $('#itemid').val().split('_');
  var itemid = split['0'];
  var lbs = $('#lbs').val();
  tempList.push(tempList['itemid'] = lbs);
  for (var i; i<=(tempList.length - 1); i++){
    if (i==0){
      var list = tempList[i]+ '<br />';
    } 
    else{
    开发者_JS百科  var list =  list + tempList[i]+ '<br />';
    }
  }
  alert(list);
});

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Old answer: Your script may not work, because you have to initialise the index of the loop: var i=0;

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Question (new, at the comment chain):

Hi, hope you dont mind another question but how do I display the content of tempList[] in a table?

Answer:
See the code below. After the loop, I have included several ways to append the data/table to the body, because you didn't specify which method you wanted.

var tempList = {};
$('#add').click(function(){
    var split = $('#itemid').val().split('_');
    var returnTable = "<thead><tr><th>ItemId</th><th>Lbs</th></tr></thead><tbody>";
    var itemid = split[0];
    if(/^\d+$/.test(itemid)) return; //itemId is not a valid number: return now.

    var lbs = $('#lbs').val();
    tempList[itemid] = lbs; //refer by value, removed quotes around `itemId`.
    for (var i in tempList){
        returnTable += "<tr><td>" + i + "</td><td>" + tempList[i] + '</td></tr>';
    }
    returnTable += "</tbody>";


    var tbl = document.createElement("table");
    tbl.innerHTML = returnTable;

    //Various methods to add the table to your document are shown below
    // For each example, I assume that that specific element exists

    //When the data should be APPENDED to an existing TABLE ("#existingTable")
    var tblTo = document.getElementById("existingTable").tBodies[0];
    for(var i=0, len=tbl.tBodies[0].rows.length; i<len; i++){
        tblTo.appendChild(tbl.tBodies[0].rows[0]);
        //Removes the row from the temporary table, appends row to tblTo
    }

    //When the new table should replace the previous table ("#prevTable"):
    var prevTbl = document.getElementById("prevTable");
    prevTbl.parentNode.replaceChild(tbl, prevTbl);

    //When the table should be APPENDED to a container ("#container")
    document.getElementById("output").appendChild(tbl);

    //When the new table should replace the contents of a container ("#container")
    var container = document.getElementById("container");
    container.innerHTML = "";
    container.appendChild(tbl);
});