[英]detect dynamically checkboxes/polymer elements ticked in Dart
Dart的新手,沒有JS經驗。 我編寫了代碼來填充JSON的下拉列表。
編輯:我正在嘗試添加聚合物元素。
聚合物.dart
import 'package:polymer/polymer.dart';
@CustomTag('player-item')
class PlayerItem extends PolymerElement{
@observable String playerName='hello';
void removePlayer(){
playerName='';
}
PlayerItem.created(): super.created(){}
}
最初是未定義構造函數的錯誤。 在super.created中添加了空括號。 已修復錯誤我在做什么錯。 如何正確做到這一點?
polymer.html
playername =要動態顯示的玩家名稱。
現在使用默認字符串。
removeplayer =(想法是)刪除整個聚合物元素。
<polymer-element name="player-item">
<template>
<input type="image" src="button_minus_red.gif" on-click="{{removePlayer}}">
<div>{{playerName}}</div>
</template>
<script type="application/dart" src="player-item.dart"></script>
</polymer-element>
編輯的Dart代碼:目標是首先生成選項,然后選擇其中一個,如果單擊圖像(用於此目的的聚合物元素),則隨后將其刪除。
通過了聚合物示例母版。 但找不到相關的東西。
需要幫助:1.如何動態添加聚合物元素?
如何將值(在這種情況下為播放器名稱)傳遞給動態添加的聚合物元素?
如何去除高分子元素?
如何刪除通過* .appendedtext添加的附加文本?
import 'dart:html';
import 'dart:convert' show JSON;
import 'dart:async' show Future;
import 'package:polymer/polymer.dart';
import 'player-item.dart';
//ButtonElement genButton,desButton;
SelectElement selectTeam;
FormElement teamPlayer;
FormElement yourPlayer;
InputElement teamPlayers;
//final subscriptions = <StreamSubscription>[];
List<String>teams=[];
List<String>players=[];
main() async{
selectTeam = querySelector('#teamNames');
teamPlayer = querySelector('#teamPlayers');
yourPlayer = querySelector('#yourPlayers');
selectTeam.onChange.listen(populateTeams);
try {
await prepareTeams1 ();
selectTeam.disabled = false; //enable
//genButton.disabled = false;
} catch(arrr) {
print('Error initializing team names: $arrr');
}
}
void populateYourPlayers(String name){
querySelector('#yourPlayers').children.add(new Element.tag('player-item'));
var input = new InputElement();
input.type = "image";
input.src = "button_minus_red.gif";
input.id = name;
print('yo');
input.width = 15;
input.height =15;
input.appendText(name);
input.onClick.listen((remove){
remove.preventDefault();
input.remove();
//yourPlayer.children.remove();
});
yourPlayer.append(input);
// yourPlayer.append(y);
yourPlayer.appendText(name);
yourPlayer.appendHtml("<br>");
}
void removeYourPlayers(Event e){
yourPlayer.querySelectorAll("input[type=checkbox]").forEach((cb) {
// print('${cb.checked}');
if(cb.checked == true){
print('${cb.id}');
yourPlayer.children.removeWhere((cb)=>cb.checked==true);
}
}
);
}
Future prepareTeams1()async{
String path = 'teams.json';
String jsonString = await HttpRequest.getString(path);
parseTeamNamesFromJSON(jsonString);
}
parseTeamNamesFromJSON(String jsonString){
Map team = JSON.decode(jsonString);
teams = team['Teams'];
print(teams);
for (int i =0; i< teams.length; i++){
var option = new OptionElement();
option.value = teams[i];
option.label =teams[i];
option.selected = false;
selectTeam.append(option);
}
}
Future prepareTeams2(String Team)async{
String path = 'teams.json';
String jsonString = await HttpRequest.getString(path);
parsePlayerNamesFromJSON(jsonString, Team);
}
parsePlayerNamesFromJSON(String jsonString,String Team){
Map team = JSON.decode(jsonString);
teamPlayer.children.clear();
teams = team[Team];
print(teams);
for (int i =0; i< teams.length; i++){
var input = new InputElement(type:"image");
// input.type = "image";
input.id = teams[i];
input.src = "button_plus_green.gif";
input.width = 15;
input.height =15;
input.onClick.listen((p){
p.preventDefault();
populateYourPlayers(teams[i]);
});
//input.onClick.listen((event){populateYourPlayers(teams[i]);});
//subscription.cancel();
teamPlayer.append(input);
teamPlayer.appendText(teams[i]);
teamPlayer.appendHtml("<br>");
}
}
void populateTeams(Event e){
print('selectTeam.length: ${selectTeam.length}');
print(selectTeam.value);
prepareTeams2(selectTeam.value);
if (selectTeam.length == 0){
}
}
修改后的HTML:
<html>
<head>
<meta charset="utf-8">
<title>Pirate badge</title>
<meta name="viewport"
content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="piratebadge.css">
<link rel="import" href="player-item.html">
</head>
<body>
<h1>Team Names</h1>
<select id="teamNames">
</select>
<h1>Team players</h1>
<form id="teamPlayers">
</form>
<div>
<button id="generateButton" disabled>Add Player/Players</button>
</div>
<h1>Your players</h1>
<form id="yourPlayers">
</form>
<player-item></player-item>
<div>
<button id="destroyButton" disabled>Remove Player/Players</button>
</div>
<script type="application/dart" src="piratebadge.dart"></script>
<script src="packages/browser/dart.js"></script>
</body>
</html>
並根據該選擇顯示帶有復選框的表單。 我面臨的問題是如何檢測到它們已選中了哪些復選框,如果是,則如何捕獲該復選框的值。
但是,它們不是動態創建的復選框。
如果上述方法有誤,請告知。
您可以閱讀CheckboxInputElement
的checked
屬性
parsePlayerNamesFromJSON(String jsonString,String Team){
Map team = JSON.decode(jsonString);
teams = team[Team];
print(teams);
for (int i =0; i< teams.length; i++){
var input = new CheckboxInputElement();
input.type = "checkbox";
input.id = "player";
input.onChange.listen((_) {
print("teamplayer ${input.checked}");
});
teamPlayer.append(input);
teamPlayer.appendText(teams[i]);
teamPlayer.appendHtml("<br>");
}
取決於何時要檢測已檢查狀態,有兩種方法。
您可以將單擊處理程序添加到“提交”按鈕,然后查詢復選框。
querySelector("input[type=submit]").onClick.listen((e) {
querySelectorAll("input[type=checkbox]").forEach((cb) {
print('${cb.id} {cb.checked}');
});
});
當前,您正在為每個復選框分配相同的ID。 這是一個不好的選擇,因為您無法知道哪個復選框代表哪個項目。
另一種方法是為每個復選框分配一個單擊處理程序,以在單擊該復選框時立即得到通知。
(我通過使用continuation和forEach而不是for來簡化了復選框的創建代碼)
teams.forEach((team) {
var input = new InputElement()
..type = "checkbox"
..id = "player"
..onClick.listen((e) {
print('${cb.id} {cb.checked}');
});
teamplayer
..append(input)
..appendText(team)
..appendHtml("<br>");
}
在這種情況下,當選擇更改時,您可能需要重置點擊通知。
import 'dart:async';
// ...
final subscriptions = <StreamSubscription>[];
// ...
subscriptions
..forEach((s) => s.cancel())
..clear();
teams.forEach((team) {
var input = new InputElement()
..type = "checkbox"
..id = "player";
subscriptions.add(input.onClick.listen((e) {
print('${cb.id} {cb.checked}');
}));
teamplayer
..append(input)
..appendText(team)
..appendHtml("<br>");
}
注意:代碼未經測試,並且我使用復選框已有一段時間。
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