微信小程序开发示例：回到顶部怎么做？

2022-04-21 管理员

　　2017年7月13日，微信小程序开发实例讲解之微信小程序回到顶部，很多人都想问微信小程序怎么做回到顶层?下面从多个方面来谈谈微信小程序回到顶层。

　　7月16日开始，阿里巴巴国际站将实施重复铺货处罚新规。对于重复铺货商品占“审核通过且已上架”商品量≥10%且重复铺货商品数≥100的商家，或者，店铺重复铺货产品数≥1000的商家，阿里巴巴国际站将根据规则进行处罚和通知。

1、如何实现点击返回顶层？

最近在研究微信小程序，被这个返回顶层给坑了一波，下面贴代码

wxml代码：

<scroll-view scroll-y style="height: 1000rpx;" scroll-top="50" enable-back-to-top="true" scroll-top="{{scrollTop.scroll_top}}" bindscroll="scrollTopFun">
<block wx:for="{{sortArr}}">
<template is="spL" data="{{item}}">template>
block>
scroll-view> 

<view class="findOur fliexBox"><contact-button type="default-light" size="15" session-from="weapp">contact-button>客服view>

<view class="callOur fliexBox" bindtap="call">电话view>
<view class="fliexBox" style=" bottom: 150rpx; border: solid 1px green;" wx:if="{{scrollTop.goTop_show}}" catchtap="goTopFun">顶层view>

js代码：

var app = getApp();
Page({
data: {
hidden: true,
list: [],
scrollTop: {
scroll_top: 0,
goTop_show: false
},
scrollHeight: 0,
floorstatus:true,
sortArr:[
{
id: 1,
img: "../../images/2.jpg",
title: "君御豪园住宅",
introduction: "杭州不限购不限贷口住宅",
money: 5000,
vperson: 115,
tperson: 0
}
],
},
scrollTopFun: function (e) {
console.log(e.detail);
if (e.detail.scrollTop > 300) {//触发gotop的显示条件 
this.setData({
'scrollTop.goTop_show': true
});
} else {
this.setData({
'scrollTop.goTop_show': false
});
}
},
goTopFun: function (e) {
var _top = this.data.scrollTop.scroll_top;//发现设置scroll-top值不能和上一次的值一样，否则无效，所以这里加了个判断 
if (_top == 0) {
_top = 1;
} else {
_top = 0;
}
this.setData({
'scrollTop.scroll_top': _top
});
},
/**
* 生命周期函数--监听页面加载
*/
onLoad: function (options) {
var that = this;
wx.getSystemInfo({
success: function (res) {
that.setData({
scrollHeight: res.windowHeight
});
}
});
},

}）

wxss代码：

.fliexBox{
width: 100rpx;
height: 50rpx;
background-color: #5db13b;
color: #ffffff;
text-align: center;
position: fixed;
right: 0rpx;
bottom: 85rpx;
border-radius: 20rpx 0rpx 0rpx 20rpx;
font-size: 26rpx;
line-height: 50rpx;
opacity: .6;
}
.callOur{
bottom: 20rpx;
}
contact-button{
opacity: 0;
position: absolute;
}

主要是需要把scroll-view 组件的高度设置起来而且不能是百分比如100%这样，可以是rpx，这样才可以监测到滑动的距离。

2、微信小程序md5加密

/* 
* A JavaScript implementation of the RSA Data Security, Inc. MD5 Message 
* Digest Algorithm, as defined in RFC 1321. 
* Version 1.1 Copyright (C) Paul Johnston 1999 - 2002. 
* Code also contributed by Greg Holt 
* See http://pajhome.org.uk/site/legal.html for details. 
*/ 

/* 
* Add integers, wrapping at 2^32. This uses 16-bit operations internally 
* to work around bugs in some JS interpreters. 
*/ 
function safe_add(x, y) 
{ 
var lsw = (x & 0xFFFF) + (y & 0xFFFF) 
var msw = (x >> 16) + (y >> 16) + (lsw >> 16) 
return (msw << 16) | (lsw & 0xFFFF) 
} 

/* 
* Bitwise rotate a 32-bit number to the left. 
*/ 
function rol(num, cnt) 
{ 
return (num << cnt) | (num >>> (32 - cnt)) 
} 

/* 
* These functions implement the four basic operations the algorithm uses. 
*/ 
function cmn(q, a, b, x, s, t) 
{ 
return safe_add(rol(safe_add(safe_add(a, q), safe_add(x, t)), s), b) 
} 
function ff(a, b, c, d, x, s, t) 
{ 
return cmn((b & c) | ((~b) & d), a, b, x, s, t) 
} 
function gg(a, b, c, d, x, s, t) 
{ 
return cmn((b & d) | (c & (~d)), a, b, x, s, t) 
} 
function hh(a, b, c, d, x, s, t) 
{ 
return cmn(b ^ c ^ d, a, b, x, s, t) 
} 
function ii(a, b, c, d, x, s, t) 
{ 
return cmn(c ^ (b | (~d)), a, b, x, s, t) 
} 

/* 
* Calculate the MD5 of an array of little-endian words, producing an array 
* of little-endian words. 
*/ 
function coreMD5(x) 
{ 
var a = 1732584193 
var b = -271733879 
var c = -1732584194 
var d = 271733878 

for(var i = 0; i < x.length; i += 16) 
{ 
var olda = a 
var oldb = b 
var oldc = c 
var oldd = d 

a = ff(a, b, c, d, x[i+ 0], 7 , -680876936) 
d = ff(d, a, b, c, x[i+ 1], 12, -389564586) 
c = ff(c, d, a, b, x[i+ 2], 17, 606105819) 
b = ff(b, c, d, a, x[i+ 3], 22, -1044525330) 
a = ff(a, b, c, d, x[i+ 4], 7 , -176418897) 
d = ff(d, a, b, c, x[i+ 5], 12, 1200080426) 
c = ff(c, d, a, b, x[i+ 6], 17, -1473231341) 
b = ff(b, c, d, a, x[i+ 7], 22, -45705983) 
a = ff(a, b, c, d, x[i+ 8], 7 , 1770035416) 
d = ff(d, a, b, c, x[i+ 9], 12, -1958414417) 
c = ff(c, d, a, b, x[i+10], 17, -42063) 
b = ff(b, c, d, a, x[i+11], 22, -1990404162) 
a = ff(a, b, c, d, x[i+12], 7 , 1804603682) 
d = ff(d, a, b, c, x[i+13], 12, -40341101) 
c = ff(c, d, a, b, x[i+14], 17, -1502002290) 
b = ff(b, c, d, a, x[i+15], 22, 1236535329) 

a = gg(a, b, c, d, x[i+ 1], 5 , -165796510) 
d = gg(d, a, b, c, x[i+ 6], 9 , -1069501632) 
c = gg(c, d, a, b, x[i+11], 14, 643717713) 
b = gg(b, c, d, a, x[i+ 0], 20, -373897302) 
a = gg(a, b, c, d, x[i+ 5], 5 , -701558691) 
d = gg(d, a, b, c, x[i+10], 9 , 38016083) 
c = gg(c, d, a, b, x[i+15], 14, -660478335) 
b = gg(b, c, d, a, x[i+ 4], 20, -405537848) 
a = gg(a, b, c, d, x[i+ 9], 5 , 568446438) 
d = gg(d, a, b, c, x[i+14], 9 , -1019803690) 
c = gg(c, d, a, b, x[i+ 3], 14, -187363961) 
b = gg(b, c, d, a, x[i+ 8], 20, 1163531501) 
a = gg(a, b, c, d, x[i+13], 5 , -1444681467) 
d = gg(d, a, b, c, x[i+ 2], 9 , -51403784) 
c = gg(c, d, a, b, x[i+ 7], 14, 1735328473) 
b = gg(b, c, d, a, x[i+12], 20, -1926607734) 

a = hh(a, b, c, d, x[i+ 5], 4 , -378558) 
d = hh(d, a, b, c, x[i+ 8], 11, -2022574463) 
c = hh(c, d, a, b, x[i+11], 16, 1839030562) 
b = hh(b, c, d, a, x[i+14], 23, -35309556) 
a = hh(a, b, c, d, x[i+ 1], 4 , -1530992060) 
d = hh(d, a, b, c, x[i+ 4], 11, 1272893353) 
c = hh(c, d, a, b, x[i+ 7], 16, -155497632) 
b = hh(b, c, d, a, x[i+10], 23, -1094730640) 
a = hh(a, b, c, d, x[i+13], 4 , 681279174) 
d = hh(d, a, b, c, x[i+ 0], 11, -358537222) 
c = hh(c, d, a, b, x[i+ 3], 16, -722521979) 
b = hh(b, c, d, a, x[i+ 6], 23, 76029189) 
a = hh(a, b, c, d, x[i+ 9], 4 , -640364487) 
d = hh(d, a, b, c, x[i+12], 11, -421815835) 
c = hh(c, d, a, b, x[i+15], 16, 530742520) 
b = hh(b, c, d, a, x[i+ 2], 23, -995338651) 

a = ii(a, b, c, d, x[i+ 0], 6 , -198630844) 
d = ii(d, a, b, c, x[i+ 7], 10, 1126891415) 
c = ii(c, d, a, b, x[i+14], 15, -1416354905) 
b = ii(b, c, d, a, x[i+ 5], 21, -57434055) 
a = ii(a, b, c, d, x[i+12], 6 , 1700485571) 
d = ii(d, a, b, c, x[i+ 3], 10, -1894986606) 
c = ii(c, d, a, b, x[i+10], 15, -1051523) 
b = ii(b, c, d, a, x[i+ 1], 21, -2054922799) 
a = ii(a, b, c, d, x[i+ 8], 6 , 1873313359) 
d = ii(d, a, b, c, x[i+15], 10, -30611744) 
c = ii(c, d, a, b, x[i+ 6], 15, -1560198380) 
b = ii(b, c, d, a, x[i+13], 21, 1309151649) 
a = ii(a, b, c, d, x[i+ 4], 6 , -145523070) 
d = ii(d, a, b, c, x[i+11], 10, -1120210379) 
c = ii(c, d, a, b, x[i+ 2], 15, 718787259) 
b = ii(b, c, d, a, x[i+ 9], 21, -343485551) 

a = safe_add(a, olda) 
b = safe_add(b, oldb) 
c = safe_add(c, oldc) 
d = safe_add(d, oldd) 
} 
return [a, b, c, d] 
} 

/* 
* Convert an array of little-endian words to a hex string. 
*/ 
function binl2hex(binarray) 
{ 
var hex_tab = "0123456789abcdef" 
var str = "" 
for(var i = 0; i < binarray.length * 4; i++) 
{ 
str += hex_tab.charAt((binarray[i>>2] >> ((i%4)*8+4)) & 0xF) + 
hex_tab.charAt((binarray[i>>2] >> ((i%4)*8)) & 0xF) 
} 
return str 
} 

/* 
* Convert an array of little-endian words to a base64 encoded string. 
*/ 
function binl2b64(binarray) 
{ 
var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" 
var str = "" 
for(var i = 0; i < binarray.length * 32; i += 6) 
{ 
str += tab.charAt(((binarray[i>>5] << (i%32)) & 0x3F) | 
((binarray[i>>5+1] >> (32-i%32)) & 0x3F)) 
} 
return str 
} 

/* 
* Convert an 8-bit character string to a sequence of 16-word blocks, stored 
* as an array, and append appropriate padding for MD4/5 calculation. 
* If any of the characters are >255, the high byte is silently ignored. 
*/ 
function str2binl(str) 
{ 
var nblk = ((str.length + 8) >> 6) + 1 // number of 16-word blocks 
var blks = new Array(nblk * 16) 
for(var i = 0; i < nblk * 16; i++) blks[i] = 0 
for(var i = 0; i < str.length; i++) 
blks[i>>2] |= (str.charCodeAt(i) & 0xFF) << ((i%4) * 8) 
blks[i>>2] |= 0x80 << ((i%4) * 8) 
blks[nblk*16-2] = str.length * 8 
return blks 
} 

/* 
* Convert a wide-character string to a sequence of 16-word blocks, stored as 
* an array, and append appropriate padding for MD4/5 calculation. 
*/ 
function strw2binl(str) 
{ 
var nblk = ((str.length + 4) >> 5) + 1 // number of 16-word blocks 
var blks = new Array(nblk * 16) 
for(var i = 0; i < nblk * 16; i++) blks[i] = 0 
for(var i = 0; i < str.length; i++) 
blks[i>>1] |= str.charCodeAt(i) << ((i%2) * 16) 
blks[i>>1] |= 0x80 << ((i%2) * 16) 
blks[nblk*16-2] = str.length * 16 
return blks 
} 

/* 
* External interface 
*/ 
function hexMD5 (str) { return binl2hex(coreMD5( str2binl(str))) } 
function hexMD5w(str) { return binl2hex(coreMD5(strw2binl(str))) } 
function b64MD5 (str) { return binl2b64(coreMD5( str2binl(str))) } 
function b64MD5w(str) { return binl2b64(coreMD5(strw2binl(str))) } 
/* Backward compatibility */ 
function calcMD5(str) { return binl2hex(coreMD5( str2binl(str))) } 
module.exports = { 
hexMD5: hexMD5 
}

//index.js    
var util = require('../../utils/md5.js')    
//获取应用实例    
var app = getApp()    
Page({    
  data: {    
    page:'1',    
  },    
   var password=value.password;    
   if(password===""||password===null){    
       wx.showModal({    
            title:'提示',    
            content: '密码不能为空',    
            confirmColor:'#118EDE',    
            showCancel: false,    
            success: function (res) {    
                if (res.confirm) {    
                    //console.log('用户点击确定')    
                }    
            }    
        });    
        return false;    
    }else{    
        password=util.hexMD5(password);    
    }    
})