微信小程序开发(2) 计算器

在这篇微信小程序开发教程中，我们将介绍如何使用微信小程序开发计算器功能。

本文主要分为两个部分，小程序主体部分及计算器业务页面部分

一、小程序主体部分

一个小程序主体部分由三个文件组成，必须放在项目的根目录，如下：



1. 小程序逻辑

App({
onLaunch: function() {
// Do something initial when launch.
},
onShow: function() {
// Do something when show.
},
onHide: function() {
// Do something when hide.
},
globalData: 'I am global data'
})

2. 小程序公共设置

{
"pages": [
"page/index/index"
],
"window": {
"navigationBarBackgroundColor": "#000",
"backgroundColor": "#000",
"navigationBarBackgroundColor": "#000"
},
"networkTimeout": {
"request": 10000,
"connectSocket": 10000,
"uploadFile": 10000,
"downloadFile": 10000
},
"debug": true
}

二、计算器页面部分

计算器页面主要由以下文件组成。



1. 计算器页面结构

页面结构分为2个主要部分：显示区和键盘区

其中键盘区又分功能键、数字键，及运算键，页面结构如下

<template name="calculator-key">
<button hover-start-time="{{5}}" hover-stay-time="{{20}}" hover-class="calculator-key-hover" data-key="{{className}}" class="calculator-key {{className}}">{{display}}</button>
</template>

<view class="calculator">
<view class="calculator-display">
<view class="calculator-display-text">{{displayValue}}</view>
</view>
<view class="calculator-keypad">
<view class="input-keys">
<view class="function-keys" catchtap="onTapFunction">
<template is="calculator-key" data="{{className: 'key-clear', display: clearDisplay ? 'C' : 'AC'}}"/>
<template is="calculator-key" data="{{className: 'key-sign', display: '±'}}"/>
<template is="calculator-key" data="{{className: 'key-percent', display: '%'}}"/>
</view>
/*sdf*/
<view class="digit-keys" catchtap="onTapDigit">
<template is="calculator-key" data="{{className: 'key-0', display: '0'}}"/>
<template is="calculator-key" data="{{className: 'key-dot', display: '●'}}"/>
<template is="calculator-key" data="{{className: 'key-1', display: '1'}}"/>
<template is="calculator-key" data="{{className: 'key-2', display: '2'}}"/>
<template is="calculator-key" data="{{className: 'key-3', display: '3'}}"/>
<template is="calculator-key" data="{{className: 'key-4', display: '4'}}"/>
<template is="calculator-key" data="{{className: 'key-5', display: '5'}}"/>
<template is="calculator-key" data="{{className: 'key-6', display: '6'}}"/>
<template is="calculator-key" data="{{className: 'key-7', display: '7'}}"/>
<template is="calculator-key" data="{{className: 'key-8', display: '8'}}"/>
<template is="calculator-key" data="{{className: 'key-9', display: '9'}}"/>
</view>
</view>
<view class="operator-keys" catchtap="onTapOperator">
<template is="calculator-key" data="{{className: 'key-divide', display: '÷'}}"/>
<template is="calculator-key" data="{{className: 'key-multiply', display: '×'}}"/>
<template is="calculator-key" data="{{className: 'key-subtract', display: '−'}}"/>
<template is="calculator-key" data="{{className: 'key-add', display: '+'}}"/>
<template is="calculator-key" data="{{className: 'key-equals', display: '='}}"/>
</view>
</view>
</view>

2. 计算器样式表

样式代码如下所示

@import "reset.wxss";

page {
font: 100 14px 'Roboto';
}

.calculator {
width: 100%;
height: 100vh;
background: black;
position: relative;
box-shadow: 0px 0px 20px 0px #aaa;
display: flex;
flex-direction: column;
box-sizing: border-box;
}

.calculator-display {
background: #1c191c;
flex: 1;
}

/*TODO:解决文本垂直居中问题*/
.calculator-display-text {
padding: 0 30px;
font-size: 6em;
color: white;
text-align: right;
}

.calculator-keypad {
display: flex;
}

.calculator .function-keys {
display: flex;
}

.calculator .digit-keys {
background: #e0e0e7;
display: flex;
flex-direction: row;
flex-wrap: wrap-reverse;
}

.calculator-key-hover {
box-shadow: inset 0px 0px 25vw 0px rgba(0,0,0,0.25);
}

.calculator-key {
display: block;
width: 25vw;
height: 25vw;
line-height: 25vw;
border-top: 1px solid #777;
border-right: 1px solid #666;
text-align: center;
box-sizing: border-box;
}

.calculator .function-keys .calculator-key {
font-size: 2em;
}

.calculator .digit-keys .calculator-key {
font-size: 2.25em;
}

.calculator .digit-keys .key-0 {
width: 50vw;
text-align: left;
padding-left: 9vw;
}

.calculator .digit-keys .key-dot {
padding-top: 1em;
font-size: 0.75em;
}

.calculator .operator-keys .calculator-key {
color: white;
border-right: 0;
font-size: 3em;
}

.calculator .function-keys {
background: linear-gradient(to bottom, rgba(202,202,204,1) 0%, rgba(196,194,204,1) 100%);
}

.calculator .operator-keys {
background:  linear-gradient(to bottom, rgba(252,156,23,1) 0%, rgba(247,126,27,1) 100%);
}

.input-keys {
width: 75%;
}

.operator-keys {
width: 25%;
}

3、 计算器页面逻辑处理

Page({
data: {
value: null, // 上次计算后的结果，null表示没有上次计算的结果
displayValue: '0', // 显示数值
operator: null, // 上次计算符号，null表示没有未完成的计算
waitingForOperand: false // 前一按键是否为计算符号
},

onLoad: function(options) {
this.calculatorOperations = {
'key-divide': (prevValue, nextValue) => prevValue / nextValue,
'key-multiply': (prevValue, nextValue) => prevValue * nextValue,
'key-add': (prevValue, nextValue) => prevValue + nextValue,
'key-subtract': (prevValue, nextValue) => prevValue - nextValue,
'key-equals': (prevValue, nextValue) => nextValue
}
},

/* AC操作，一下回到解放前 */
clearAll() {
this.setData({
value: null,
displayValue: '0',
operator: null,
waitingForOperand: false
})
},

/* 仅清空当前显示的输入值 */
clearDisplay() {
this.setData({
displayValue: '0'
})
},

onTapFunction: function(event) {
const key = event.target.dataset.key;

switch(key) {
case 'key-clear':
if (this.data.displayValue !== '0') {
this.clearDisplay();
} else {
this.clearAll();
}

break;

case 'key-sign':
var newValue = parseFloat(this.data.displayValue) * -1

this.setData({
displayValue: String(newValue)
})

break;

case 'key-percent':
const fixedDigits = this.data.displayValue.replace(/^-?\d*\.?/, '')
var newValue = parseFloat(this.data.displayValue) / 100

this.setData({
displayValue: String(newValue.toFixed(fixedDigits.length + 2))
});

break;

default:
break;
}
},

onTapOperator: function(event) {
const nextOperator = event.target.dataset.key;
const inputValue = parseFloat(this.data.displayValue);

if (this.data.value == null) {
this.setData({
value: inputValue
});
} else if (this.data.operator) {
const currentValue = this.data.value || 0;
const newValue = this.calculatorOperations[this.data.operator](currentValue, inputValue);

this.setData({
value: newValue,
displayValue: String(newValue)
});
}

this.setData({
waitingForOperand: true,
operator: nextOperator
});
},

onTapDigit: function(event) {
const key = event.target.dataset.key; // 根据data-key标记按键

if(key == 'key-dot') {
// 按下点号
if (!(/\./).test(this.data.displayValue)) {
this.setData({
displayValue: this.data.displayValue + '.',
waitingForOperand: false
})
}
} else {
// 按下数字键
const digit = key[key.length-1];

if (this.data.waitingForOperand) {
this.setData({
displayValue: String(digit),
waitingForOperand: false
})
} else {
this.setData({
displayValue: this.data.displayValue === '0' ? String(digit) : this.data.displayValue + digit
})
}
}
}
})

三、程序效果图

四、源代码下载

扫描下方二维码并关注公众账号，回复 “1236” 获取



源代码使用方法，请参考 微信小程序开发入门教程