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:169Please respect copyright.PENANAPesv84a6Yn
---read whole file content into array buffer---169Please respect copyright.PENANA7AtUeeyH38
let file=input.files[0]; const reader = new FileReader(); 169Please respect copyright.PENANAgoKQa9RvC2
reader.onload = () => 169Please respect copyright.PENANAemwXsV4eh1
{169Please respect copyright.PENANAsXHnxF9lkb
let content_whole = new Uint8Array(reader.result);169Please respect copyright.PENANAK6u5EWIJFe
}169Please respect copyright.PENANAmhI8NzYElh
reader.readAsArrayBuffer(file);169Please respect copyright.PENANAyxQgOsYFmW
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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:169Please respect copyright.PENANAXR8ZqiC7mC
---read part of file content into array buffer---169Please respect copyright.PENANAMdY4wyQmTP
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 169Please respect copyright.PENANAP2PMV4TXsa
reader.onload = () => 169Please respect copyright.PENANAL8PKmgKcTO
{169Please respect copyright.PENANAJqK8JAgPXd
let content_part = new Uint8Array(reader.result);169Please respect copyright.PENANA1ay4SkZhBN
}169Please respect copyright.PENANAYocmgIoQSQ
reader.readAsArrayBuffer(file.slice(start,end));169Please respect copyright.PENANABUYZfCTHwW
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169Please respect copyright.PENANA0ePlawCmBK
Section X. Thanks169Please respect copyright.PENANAT3YSFAznuo
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]169Please respect copyright.PENANAplw2DCUunX
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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