为什么" $ P $砰砰"函数是在角度指令`ngForm`使用,而不是常规的" postLink"功能? [英] Why a "preLink" function is used in angular directive `ngForm`, instead of regular "postLink" function?
问题描述
里面angular.js,在ngForm(形式)指令的定义,编译函数仅返回 $ P $砰砰
功能。为什么它应该是 $ P $砰砰
,而不是常见的 postLink
?
以下code是angular.js主分支:
VAR formDirective = {
名称:'形式',
限制:isNgForm? EAC':'E',
控制器:的FormController,
编译:功能ngFormCompile(formElement){
//设置控件的初始状态
formElement.addClass(PRISTINE_CLASS).addClass(VALID_CLASS);
返回{
pre:功能ngForm $ P $砰砰(范围,formElement,ATTR,控制器){
//如果`action` attr为没有在表格上present,prevent默认操作(提交)
如果(!(在ATTR'行动')){
//我们不能用JQ事件,因为如果表单提交的默认期间被毁
//动作不pvented $ P $。见#1238
//
// IE 9不会受到影响,因为它不火提交事件,并尝试做一个完整的
//如果表单被提交表单通过点击摧毁处理页面重载
//在表格的按钮。看起来像IE9的具体错误。
VAR handleFormSubmission =函数(事件){
范围。$应用(函数(){
控制器$ commitViewValue()。
控制器$ setSubmitted()。
});
。事件preventDefault();
};
...
所以这是一个好地方,prepare将由子指令中的任何数据的任何儿童指令之前执行的pre-Link功能。我presume在这种情况下,prepares的情况下的子指令提交表单在其链路交函数提交处理程序。
在实践中的链接功能执行的顺序是:
- 母公司pre-链接
- 子pre-链接
- 子后链接
- 父后链接
Inside angular.js, in ngForm (form) directive definition, compile function returns only a preLink
function. Why it should be preLink
instead of common postLink
?
The following code is from angular.js master branch:
var formDirective = {
name: 'form',
restrict: isNgForm ? 'EAC' : 'E',
controller: FormController,
compile: function ngFormCompile(formElement) {
// Setup initial state of the control
formElement.addClass(PRISTINE_CLASS).addClass(VALID_CLASS);
return {
pre: function ngFormPreLink(scope, formElement, attr, controller) {
// if `action` attr is not present on the form, prevent the default action (submission)
if (!('action' in attr)) {
// we can't use jq events because if a form is destroyed during submission the default
// action is not prevented. see #1238
//
// IE 9 is not affected because it doesn't fire a submit event and try to do a full
// page reload if the form was destroyed by submission of the form via a click handler
// on a button in the form. Looks like an IE9 specific bug.
var handleFormSubmission = function(event) {
scope.$apply(function() {
controller.$commitViewValue();
controller.$setSubmitted();
});
event.preventDefault();
};
...
The pre-link function is executed before any child directives so it's a good place to prepare any data to be used by child directives. I presume in this case it prepares the submission handler in case a child directive submits the form in its post-link function.
In practice the order of execution of link functions is:
- parent pre-link
- child pre-link
- child post-link
- parent post-link
这篇关于为什么" $ P $砰砰"函数是在角度指令`ngForm`使用,而不是常规的" postLink"功能?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!