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Learn mobile development and native applications in JavaScript
- PHPzOriginal
- 2023-11-04 08:44:41870browse
Learning mobile development and native applications in JavaScript requires specific code examples
With the popularity of smartphones, mobile development has attracted more and more attention. As a popular scripting language, JavaScript plays an important role in mobile development. This article will introduce the basics of mobile development and provide some practical code examples.
1. Basic knowledge of mobile terminal development
- Responsive layout
The screen sizes of mobile devices are various, so it is necessary to use responsive layout. Adapt to different screen sizes. Responsive layout is a design method that automatically adjusts the layout of the page according to changes in screen size.
The following is a basic responsive layout code example:
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
.container {
border: 1px solid red;
width: 100%;
padding-top: 50%;
}
.box {
background-color: blue;
height: 50px;
width: 50px;
margin-top: -25px;
margin-left: -25px;
position: absolute;
left: 50%;
top: 50%;
}
</style>
</head>
<body>
<div class="container">
<div class="box"></div>
</div>
</body>
</html>In this code, the meta tag is used to set the viewport width and scaling of the web page. The .container class sets the border to red and the width to 100%. The .box class sets the background color to blue, and displays the small box in the center by setting the margin and position properties. This layout automatically adapts to different screen sizes.
- Mobile Touch Events
Mobile devices differ from traditional mouse and keyboard input in that they use touch screens for user interaction. JavaScript provides a series of touch events to respond to user touch operations, such as touchstart, touchmove, touchend, etc.
The following is a code example using touch events:
<!DOCTYPE html>
<html>
<head>
<style>
.box {
width: 100px;
height: 100px;
background-color: red;
}
</style>
</head>
<body>
<div class="box"></div>
<script>
var box = document.querySelector('.box');
box.addEventListener('touchstart', function(event) {
event.preventDefault();
box.style.backgroundColor = 'blue';
});
box.addEventListener('touchend', function(event) {
event.preventDefault();
box.style.backgroundColor = 'red';
});
</script>
</body>
</html>In this code, first use the querySelector method to obtain the .box element and add a touch event listener to it. In the handler function of the touchstart event, set the background color of the .box element to blue; in the handler function of the touchend event, return the background color to red. This way, when the user touches the .box element, its background color changes.
2. Examples of JavaScript native applications
In addition to mobile development, JavaScript can also be used to develop native applications. Native applications refer to cross-platform applications developed through JavaScript and related technologies and can run on different operating systems.
The following is a code example of a native application developed using React Native:
import React, { Component } from 'react';
import { View, Text, StyleSheet } from 'react-native';
export default class App extends Component {
render() {
return (
<View style={styles.container}>
<Text style={styles.text}>Hello, world!</Text>
</View>
);
}
}
const styles = StyleSheet.create({
container: {
flex: 1,
justifyContent: 'center',
alignItems: 'center',
},
text: {
fontSize: 20,
fontWeight: 'bold',
},
});This code uses the React Native framework to develop native applications. In the render method, return a component containing a view and a text. Among them, the style uses Flexbox layout and sets the alignment of the view and the font size and thickness of the text.
Through this code example, you can see the development methods and characteristics of JavaScript native applications. Using React Native, you can use JavaScript to develop native applications for iOS and Android without needing to learn native languages such as Objective-C, Swift or Java.
Summary:
This article introduces the basic knowledge of JavaScript in mobile development and native application development, and provides some specific code examples. During the learning process, you can practice based on actual projects to deepen your understanding of mobile terminal development and native application development. Hope this article will be helpful to you.
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