微信小程序開發之好友列表字母列表跳轉對應位置

前言：

在小程序里實現微信好友列表點擊右側字母列表跳轉對應位置效果。寫了個demo，核心部分很簡單，所以沒多少注釋，如果遇到問題就加群問我吧。

核心技術點：

1、小程序scroll-view組件的scroll-into-view， scroll-with-animation. scroll-y屬性。
2、小程序的touch事件的應用。
3、Js定時器的應用。

view頁面代碼：

index.wxml

 class="container" scroll-y>  class="info" id="info" scroll-with-animation scroll-y scroll-top="200" scroll-into-view="{{toView}}" style="height:{{height}}px;">   class="iitem" id="{{item.id}}" wx:for="{{info_list}}" wx:key="1">   {{item.id}} . {{item.desc}}     class="letter {{active == true ? 'active': ''}}" bindtouchstart='start' bindtouchmove='move' bindtouchend='end'>   class="litem" bindtap='down' data-index="999">☆   class="litem" wx:for="{{letter_list}}" bindtap='down' wx:for-index="index" wx:key="2" data-index="{{index}}" style="height: {{letter_height}}px;">{{item}}  class="tips" hidden="{{hide}}">{{curView}}

js代碼：

index.js

//index.js//獲取應用實例const app = getApp()Page({ data: {  letter_list: [],  info_list: [],  hide: true,  active: false,  toView: 'A',  curView: 'A',  letter_height: 18 }, onLoad: function () {  this.active = false;  this.timer = null;  var letter_list = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'];  var info_list = [];  for (var i = 0; i < 26; i++) {   var obj = {};   obj.id = letter_list;   obj.desc = '這是一個用于測試的DEMO。1.目標是用于實現微信好友列表的點擊首字母跳轉到對應好友位置。2.目標是用于實現微信好友列表的點擊首字母跳轉到對應好友位置';   info_list.push(obj);  }  this.setData({   height: app.globalData.height,   info_list: info_list,   letter_list: letter_list,   sHeight: 100 * 26 + 25  }); }, start: function (e) {  this.setData({   active: true,   hide: false  }) }, end: function (e) {  if (this.timer) {   clearTimeout(this.timer);   this.timer = null;  }  var moveY = e.changedTouches["0"].clientY - 18, that = this;  var curIndex = parseInt(moveY / 18);  var view = this.data.letter_list[curIndex];  this.setData({   toView: view,   active: false  });  if (!this.timer) {   this.timer = setTimeout(function () {    that.setData({     hide: true    })    that.timer = null;   }, 1000);  } }, move: function (e) {  var moveY = e.changedTouches["0"].clientY - 18;  var curIndex = parseInt(moveY / 18);  var view = this.data.letter_list[curIndex];  this.setData({   curView: view  }) }, down: function (e) {  if (this.timer) {   clearTimeout(this.timer);   this.timer = null;  }  var index = e.currentTarget.dataset.index,   that = this;  if (index != 999) {   var view = this.data.letter_list[index];   this.setData({    toView: view,    curView: view   })  } else {   this.setData({    toView: 'A',    curView: '☆'   })  }  if (!this.timer) {   this.timer = setTimeout(function () {    that.setData({     hide: true    });    that.timer = null;   }, 1000);  } }})