javascript - 一个页面中有多少个 watch ？

Question

我正在 Angular 中进行性能测试，我想确切地知道我的页面中有多少个 watch 。事实证明，没有简单的方法可以做到这一点。有人尝试过吗？

任何帮助将不胜感激!

Answer 1

我也有同样的问题。我创建了一个可以执行此操作的函数:

// get the watch count
// scopeHash is an optional parameter, but if you provide one, this function will modify it for later use (possibly debugging)
function getWatchCount (scope, scopeHash) {
    // default for scopeHash
    if (scopeHash === undefined) {
        scopeHash = {};
    }

    // make sure scope is defined and we haven't already processed this scope
    if (!scope || scopeHash[scope.$id] !== undefined) {
        return 0;
    }

    var watchCount = 0;

    if (scope.$$watchers) {
        watchCount = scope.$$watchers.length;
    }
    scopeHash[scope.$id] = watchCount;

    // get the counts of children and sibling scopes
    // we only need childHead and nextSibling (not childTail or prevSibling)
    watchCount+= getWatchCount(scope.$$childHead, scopeHash);
    watchCount+= getWatchCount(scope.$$nextSibling, scopeHash);

    return watchCount;
}

它将计算任何范围内的观察者数量。在根作用域上进行计算可能最有用，但您可以在任何作用域级别使用它(可能是为了检查组件上的监视)。这是一个实际示例:http://jsfiddle.net/S7APg/