AngularJS - 指令渲染完成后如何查询 DOM

问题描述

我正在尝试使用 AngularJS 指令实现自定义滚动窗格组件.在下面的

很遗憾，无法确定渲染何时完成(例如，没有事件).使用 $timeout 似乎是最好的解决方法.

在上面的链接中，@Nik 在评论中提到他正在检查 $('tr').length >3，针对他的特定场景，确定渲染何时完成.也许您可以定期检查 DOM 中的某些内容以确定渲染是否完成.

I'm trying to implement a custom scroll pane component using an AngularJS directive. in the following jsfiddle example I have an example of the basic prototype.

here is a schema of my idea:

Here is the directive code:

    myApp.directive('lpScrollPane', function factory() {
    return {
        restrict: 'A',
        replace: true,
        transclude: true,
        template: '<div class="scrollPaneWrapper"><div class="scrollPane" ng-transclude></div><div class="thumbTrack" ></div></div>',
        compile: function (tElement, tAttrs) {
            var minHeight = 30;
            return function (scope, iElement, iAttrs) {
                var thumbTrack = angular.element(iElement.children()[1]);

                scope.onScrollHeight = function () {
                    console.log(iElement.children()[0].scrollHeight);

                    var H1 = iElement[0].offsetHeight;
                    var H2 = iElement.children()[0].scrollHeight;
                    if (H2 > H1) {
                        var trackHeight = Math.round(minHeight + (H1 - minHeight) * (1 - Math.pow((H2 - H1) / H2, 0.8)));
                        thumbTrack.css({
                            display: "block",
                            height: trackHeight + "px"
                        });
                        console.log(H2, H1, trackHeight);
                    } else {
                        thumbTrack.css({
                            display: "none"
                        });
                    }
                };

                scope.$watch(function () {
                    scope.onScrollHeight();
                    //setTimeout(scope.onScrollHeight, 100)
                });


            }
        }
    };
});

Basically there are 2 dives 1 with overflow hidden and one with overflow scroll and another div to mimic the thumb tracker.

My Goal is to monitor the scrollHeight property and then change the tracker height accordingly. the issue is the $watch gets fired before the DOM is rendered so there is a delay in showing and calculating the tracker. For now I used setTimeout on the watch function and it works fine (un-comment line 35 and comment 34 to see it in action).

What would be the right way to do it?

See is there a post render callback for Angular JS directive?

Unfortunately, there is no way to determine when rendering is complete (e.g., there is no event). Using $timeout seems to be the best workaround available.

In the link above, @Nik mentioned in a comment that he was checking $('tr').length > 3, for his particular scenario, to determine when rendering was complete. Maybe there is something you could periodically examine in the DOM to determine that rendering is complete.

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