本文描述了使用javascript读取用户通过Input控件选择的文件的内容的方法和注意事项。后面用英文写,但我的英文不太好,如有错误之处,希望大家帮我纠正,我的联系方式在后面。
When user select a file by <input type=file>, its content can be read by javascript like this:178Please respect copyright.PENANApFa0xQZDx0
---read whole file content into array buffer---178Please respect copyright.PENANAGoekjPnEBj
let file=input.files[0]; const reader = new FileReader(); 178Please respect copyright.PENANAytFOUQOEDB
reader.onload = () => 178Please respect copyright.PENANANdHP0Lht7R
{178Please respect copyright.PENANA2wFwxSyX2n
let content_whole = new Uint8Array(reader.result);178Please respect copyright.PENANA9Jv8u8LTMD
}178Please respect copyright.PENANAYKA6Mjsmtt
reader.readAsArrayBuffer(file);178Please respect copyright.PENANAY3GOhQL1VA
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If the file size is too large, the browser may crash as the whole file content are loaded into memory by array buffer. In order to avoid it, we can just read a part of the file like this:178Please respect copyright.PENANA3Tmh2DhcNn
---read part of file content into array buffer---178Please respect copyright.PENANAhQKKDxXTPH
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 178Please respect copyright.PENANAAvFBtBcKP9
reader.onload = () => 178Please respect copyright.PENANAnLRIF1qUhO
{178Please respect copyright.PENANAYbKaVJQ39l
let content_part = new Uint8Array(reader.result);178Please respect copyright.PENANAjwONVuisNw
}178Please respect copyright.PENANAmDJxqQWc4D
reader.readAsArrayBuffer(file.slice(start,end));178Please respect copyright.PENANAn8xlAWN7VC
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178Please respect copyright.PENANAlj7muZ08Pq
Section X. Thanks178Please respect copyright.PENANAGg0Pmg8rj5
https://segmentfault.com/a/1190000022113605
Section Y. Contacts Me
If you found any errors or have any suggestions for this article, please let me know, my wechat: si_jinmin, my email: [email protected]178Please respect copyright.PENANA5AHJEBqqZN
如果您发现本文有任何错误,或者对本文有好的建议,欢迎与我联系探讨,我的微信: si_jinmin, 我的email: [email protected]
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