最大化$ digest迭代

Question

我=在这个小提琴中玩弄指令和绑定。我收到以下错误：

Uncaught Error: 10 $digest() iterations reached. Aborting!
Watchers fired in the last 5 iterations: [["fn: function () {\n                  var parentValue = parentGet(parentScope);\n\n                  if (parentValue !== scope[scopeName]) {\n                    // we are out of sync and need to copy\n                    if (parentValue !== lastValue) {\n                      // parent changed and it has precedence\n                      lastValue = scope[scopeName] = parentValue;\n                    } else {\n                      // if the parent can be assigned then do so\n                      parentSet(parentScope, lastValue = scope[scopeName]);\n                    }\n                  }\n                  return parentValue;\n                }; newVal: {\"baz\":3}; oldVal: {\"baz\":3}"],["fn: function () {\n                  var parentValue = parentGet(parentScope);\n\n                  if (parentValue !== scope[scopeName]) {\n                    // we are out of sync and need to copy\n                    if (parentValue !== lastValue) {\n                      // parent changed and it has precedence\n                      lastValue = scope[scopeName] = parentValue;\n                    } else {\n                      // if the parent can be assigned then do so\n                      parentSet(parentScope, lastValue = scope[scopeName]);\n                    }\n                  }\n                  return parentValue;\n                }; newVal: {\"baz\":3}; oldVal: {\"baz\":3}"],["fn: function () {\n                  var parentValue = parentGet(parentScope);\n\n                  if (parentValue !== scope[scopeName]) {\n                    // we are out of sync and need to copy\n                    if (parentValue !== lastValue) {\n                      // parent changed and it has precedence\n                      lastValue = scope[scopeName] = parentValue;\n                    } else {\n                      // if the parent can be assigned then do so\n                      parentSet(parentScope, lastValue = scope[scopeName]);\n                    }\n                  }\n                  return parentValue;\n                }; newVal: {\"baz\":3}; oldVal: {\"baz\":3}"],["fn: function () {\n                  var parentValue = parentGet(parentScope);\n\n                  if (parentValue !== scope[scopeName]) {\n                    // we are out of sync and need to copy\n                    if (parentValue !== lastValue) {\n                      // parent changed and it has precedence\n                      lastValue = scope[scopeName] = parentValue;\n                    } else {\n                      // if the parent can be assigned then do so\n                      parentSet(parentScope, lastValue = scope[scopeName]);\n                    }\n                  }\n                  return parentValue;\n                }; newVal: {\"baz\":3}; oldVal: {\"baz\":3}"],["fn: function () {\n                  var parentValue = parentGet(parentScope);\n\n                  if (parentValue !== scope[scopeName]) {\n                    // we are out of sync and need to copy\n                    if (parentValue !== lastValue) {\n                      // parent changed and it has precedence\n                      lastValue = scope[scopeName] = parentValue;\n                    } else {\n                      // if the parent can be assigned then do so\n                      parentSet(parentScope, lastValue = scope[scopeName]);\n                    }\n                  }\n                  return parentValue;\n                }; newVal: {\"baz\":3}; oldVal: {\"baz\":3}"]] angular.js:7729
Scope.$digest angular.js:7729
Scope.$apply angular.js:7894
(anonymous function) angular.js:930
invoke angular.js:2788
bootstrap angular.js:928
angularInit angular.js:904
(anonymous function) angular.js:14397
trigger angular.js:1695
(anonymous function) angular.js:1930
forEach angular.js:110
eventHandler angular.js:1929

为什么会这样呢？我认为这与=绑定有关。

Answer 1

这是因为它在每次经历摘要周期时都在创建一个全新的对象。监视在此=数据绑定中注册，因此每次它评估bar="{baz: 3}"一个新对象时都会创建它，因此它将与以前的值不同，从而触发另一个摘要循环。最终，它终止，因此不会无限循环。有关更详尽的说明，请参见http://docs.angularjs.org/guide/concepts#runtime。

诀窍是=使用不会每次更改的参考进行数据处理。这通常是通过将其置于指令之外的范围内来完成的。参见http://jsfiddle.net/u4BTu/7/