How to use HTML and JavaScript to convert strings to numbers-Front-end Q&A-php.cn

How to use HTML and JavaScript to convert strings to numbers

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Release： 2023-04-06 11:05:24

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In recent years, Web front-end technology has become more and more important with the rapid development of the Internet, among which HTML and JavaScript languages are indispensable basic technologies. In the front-end development process, converting strings to numbers is a common requirement, especially in data processing. This article will introduce how to use HTML and JavaScript to implement the string to number function.

1. Preliminary understanding of HTML and JavaScript

Before explaining how to convert strings to numbers, let’s first briefly understand HTML and JavaScript.

HTML: The full name is Hyper Text Markup Language, which is translated into Chinese as hypertext markup language. It is a standard markup language used to create web pages.
JavaScript: An object- and event-driven scripting language, mainly used for Web front-end development, such as dynamic effects, data interaction, data verification and other functions.

2. Method of converting string to number

In JavaScript, we can use parseInt(), parseFloat(), Number() and other functions to perform string to number operations. . The specific usage is as follows:

parseInt() function

The parseInt() function can convert a string into an integer. Its syntax format is:

parseInt(string, radix)

Among them, string represents the string to be converted, and radix represents the base number. If the radix parameter is omitted, conversion will be performed in decimal format by default.

The following is a simple sample code:

var str = "123abc";
var num = parseInt(str);
console.log(num);

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The output result of the above code is 123.

parseFloat() function

The parseFloat() function is used to convert a string to a floating point number. Its syntax format is:

parseFloat(string)

where string represents the string to be converted.

The following is a simple sample code:

var str = "3.14abc";
var num = parseFloat(str);
console.log(num);

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The output result of the above code is 3.14.

Number() function

TheNumber() function is used to convert a string to a numeric type. Its syntax format is:

Number(string)

where string represents the string to be converted.

The following is a simple sample code:

var str = "123.45abc";
var num = Number(str);
console.log(num);

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The output result of the above code is 123.45.

3. Practical Exercise

Below we can use practical examples to demonstrate how to implement the function of converting strings to numbers.

HTML code:

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>字符串转数字</title>
</head>
<body>
    <label>请输入要转换的字符串：</label>
    <input type="text" id="inputStr" />
    <br/><br/>
    <button type="button" onclick="convert()">转换</button>
    <br/><br/>
    <label>转换后的结果：</label>
    <span id="outputNum"></span>
</body>
<script>
    function convert() {
        var inputStr = document.getElementById("inputStr").value;
        var num = Number(inputStr);
        document.getElementById("outputNum").innerHTML = num;
    }
</script>
</html>

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JavaScript code analysis:

First, we need to get the string entered by the user on the page, use the following code to get it:

var inputStr = document.getElementById("inputStr").value;

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Then, we use the Number() function to convert the obtained string into a numeric type, and display the result on the page, using the following code:

var num = Number(inputStr);
document.getElementById("outputNum").innerHTML = num;

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3. Summary

Through the introduction of this article, we have learned how to use HTML and JavaScript to implement the function of converting strings to numbers. In actual development, converting strings to numbers is a common data processing requirement. Mastering the methods introduced in this article is very necessary for Web front-end developers. At the same time, we also need to pay attention to the need to ensure the accuracy and precision of the data during the conversion process.

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