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Web pages cannot read files directly and need to use front-end frameworks or libraries. Commonly used methods include: XMLHttpRequest object: used for asynchronous data exchange, which can obtain file content by creating objects, opening requests, sending requests, and processing responses. FileReader object: used to read local files. The file content can be obtained by creating objects, adding event handling functions and calling methods. AJAX framework: Provides simpler syntax, such as the $.get() function in jQuery, making reading files more convenient.
How to read files from web pages
HTML itself cannot read files directly. In order to read the file, you need to use a front-end framework or library. The following are the most commonly used methods:
XMLHttpRequest
The XMLHttpRequest object is used for asynchronous data exchange with the server. It allows web pages to read files without refreshing the entire page. The usage steps are as follows:
onload
event listener. responseText
property to get the file content. FileReader
The FileReader object is used to read files, usually used to handle local file uploads. The usage steps are as follows:
onload
event listener to run after the file reading is completed. readAsText()
method to read the file content as text. onload
event handler function, use the result
attribute to obtain the file content. AJAX Framework
AJAX frameworks such as jQuery provide a simplified syntax for reading files. For example, reading a text file using jQuery:
<code class="javascript">$.get('file.txt', function(data) { // 在此处理文件内容 });</code>
Other methods
There are some other ways to read files, but they are less used:
contentDocument
attribute. fetch()
function. It returns a Promise that resolves after the read is complete. Which method to choose
Which method to choose depends on the specific needs:
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