TypeError: grid.columns[0] is undefined in Firefox Vaadin Grid

TypeError: grid.columns[0] is undefined in Firefox Vaadin Grid

我正在使用 vaadin 网格。我得到:

TypeError: grid.columns[0] is undefined

如标题所示,在 Firefox 中。在 Chrome 它正在工作。代码:

var grid = grid || document.querySelector('vaadin-grid');
HTMLImports.whenReady(function() {
    var json = '[["Blabla", true, "sdfsdfsd", "fsdsdfsdfsd fsdfds fsdf shfskd hds", 0, "39acbfa4-6d6b-4af9-b872-03fc70328183"]]';

    var testJSON = JSON.parse(json);
    grid.items = testJSON;

    // --> ERROR: undefined in firefox
    grid.columns[0].renderer = function(cell) {
        //...
    };    
});

为什么?

找到后:

我可以解决我的问题:

使用 window.addEventListener('WebComponentsReady', function(e){ 而不是

HTMLImports.whenReady(function() {

像这样:

var grid = grid || document.querySelector('vaadin-grid');
window.addEventListener('WebComponentsReady', function(e) {
  var json = '[["Blabla", true, "sdfsdfsd", "fsdsdfsdfsd fsdfds fsdf shfskd hds", 0, "39acbfa4-6d6b-4af9-b872-03fc70328183"]]';

  var testJSON = JSON.parse(json);
  grid.items = testJSON;

  grid.columns[0].renderer = function(cell) {
    //...
  };    
});