[英]iron-form addEventListener of null
关于这里已经问过的问题
但是这个问题从未得到回答。
我正在尝试在铁窗体上添加eventListener:
我的HTML导入:
<link rel="import" href="/bower_components/polymer/polymer.html">
<link rel="import" href="/bower_components/iron-ajax/iron-ajax.html">
<link rel="import" href="/bower_components/iron-form/iron-form.html">
<link rel="import" href="/bower_components/paper-input/paper-input.html">
<link rel="import" href="/bower_components/paper-button/paper-button.html">
<link rel="import" href="/bower_components/paper-spinner/paper-spinner.html">
表格:
<form is="iron-form" method="get" action="/" id="eventsDemo">
<paper-input name="name" label="Name" required auto-validate></paper-input>
<paper-input name="password" label="Password" type="password" required auto-validate></paper-input>
<paper-checkbox name="read" required>You must check this box</paper-checkbox>
<br>
<paper-button raised onclick="_delayedSubmit(event)" disabled id="eventsDemoSubmit">
<paper-spinner id="spinner" hidden></paper-spinner>
Submit
</paper-button>
<paper-button raised onclick="_reset(event)">Reset</paper-button>
<div class="output"></div>
</form>
和听众:
document.getElementById('eventsDemo').addEventListener('iron-form-submit', function (event) {
});
但这也给我带来了错误-
未捕获的TypeError:无法读取null的属性'addEventListener'
我已经使用window.onload或WebComponentsReady尝试了一些建议。 没有任何帮助。
也许您缺少}或Bower安装
我找到了解决方案:
我在错误的地方定义了addEventListener,它需要与connectedCallback()中的shadowRoot一起使用。
class UserApp extends Polymer.Element {
static get is() {
return 'user-app';
}
connectedCallback() {
super.connectedCallback();
let eventsDemo = this.shadowRoot.getElementById('eventsDemo');
let eventsDemoSubmit = this.shadowRoot.getElementById('eventsDemoSubmit');
eventsDemo.addEventListener('iron-form-submit', function (event) {
console.log("iron form submit");
eventsDemoSubmit.disabled = false;
this.querySelector('.output').innerHTML = JSON.stringify(event.detail);
});
eventsDemo.addEventListener('change', function (event) {
eventsDemoSubmit.disabled = !eventsDemo.validate;
});
}
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