JavaScript to read SharePoint list items

<script type="text/javascript" style="font-size: 14px">


 $(function(){
SP.SOD.executeOrDelayUntilScriptLoaded(execClientOM, 'SP.js');

})
function execClientOM() {
alert("exe");
    context = SP.ClientContext.get_current();
alert(context);
    var list = context.get_web().get_lists().getByTitle("Programmes");
    var camlQuery = SP.CamlQuery.createAllItemsQuery();
    this.listItems = list.getItems(camlQuery);

    context.load(listItems);

    context.executeQueryAsync(ReadListItemSucceeded,
                              ReadListItemFailed);
}

function ReadListItemSucceeded(sender, args) {
    var itemsString = '';
    var enumerator = listItems.getEnumerator();

    while (enumerator.moveNext()) {
        var listItem = enumerator.get_current();
        itemsString += listItem.get_item('Title') + '\n';
    }

    alert(itemsString);
}

function ReadListItemFailed(sender, args) {
    alert('Request failed. ' + args.get_message() + '\n' +
          args.get_stackTrace());
} </script>