正如我在这里阅读（performance of $interpolate vs ng-repeat and one time binding）具有指令ng-repeat并且使用一次性绑定在性能方面几乎相同。如果这不对，请纠正我！
这意味着，在ng-repeat上使用一次性绑定时，属性track by不会添加任何值，对吗？或者它在性能方面实际上对我有帮助，因为ng-repeat否则仍会在$$hashKey生成索引？
答案 0 :(得分：1)
这意味着，当在ng-repeat上使用一次性绑定时，属性跟踪不会添加任何值，对吧？
date month year type expenditure details
[1,] "10/31/2017" "Oct" "2017" "food" "10.89" "10.89 Point Of Sale Withdrawal 17203473997 TRESIDDER U2 STANFORD CAUS"
[2,] "10/31/2017" "Oct" "2017" "uber" "4.80" "4.80 Point Of Sale Withdrawal 44519795098 UBER TRIP F73MU HELP.UBER.COMCAUS"
[3,] "10/31/2017" "Oct" "2017" "instacart" "99.00" "99.00 Point Of Sale Withdrawal 44534891998 INSTACART SUBSCRIPTION HTTPSINSTACARCAUS"
[4,] "10/31/2017" "Oct" "2017" "food" "8.45" "8.45 Point Of Sale Withdrawal 22607113998 CLARK CENTER-BIO-X CAF STANFORD CAUS"
[5,] "10/31/2017" "Oct" "2017" "food" "4.00" "4.00 Point Of Sale Withdrawal 33426639883 COUPA CAFE Y2E2 STANFORD CAUS"
[6,] "10/31/2017" "Oct" "2017" "uber" "4.52" "4.52 Point Of Sale Withdrawal 42029000200217 UBER TRIP QZ7W5 HELP.UB800-5928996 CAUS"
[7,] "10/30/2017" "Oct" "2017" "food" "5.85" "5.85 Point Of Sale Withdrawal 44519950998 UBER TRIP HOOMP HELP.UBER.COMCAUS"
[8,] "10/30/2017" "Oct" "2017" "uber" "23.20" "23.20 Point Of Sale Withdrawal 33428390882 COUPA CAFE LYTTON PALO ALTO CAUS"
[9,] "10/30/2017" "Oct" "2017" "food" "7.52" "7.52 Point Of Sale Withdrawal 34530890882 PANDA EXPRESS #2035 STANFORD CAUS"
和一次性绑定之间没有相关性。
track by不会重新呈现DOM，并且它们没有变化（假设基于项目的track by） id a.e中的一次性绑定ng-repeat一旦稳定就会停止重新计算ng-repeat="friend in ::friends"，这在第一个摘要周期后发生（如果表达式结果是非未定义的值）。
例如：
friends和
<li ng-repeat="friend in ::friends ">{{friend.name}}</li>
结果：
您将看到$scope.friends = [{
id: 0,
name: 'Ben'
}];
$timeout(function(){
$scope.friends.push({
id: 3,
name: 'Chen'
});
},1000);
但是在1秒延迟后没有变化，因为一次性绑定停止了Ben观察者。我们通常将它用于固定列表。
顺便说一句，它适用于列表项计数而不是项目本身。
一次性绑定不会消除ng-repeat
但你可以写：
$$hashKey