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:158Please respect copyright.PENANAAUHbVmhM7X
---read whole file content into array buffer---158Please respect copyright.PENANA22xrDdYgnN
let file=input.files[0]; const reader = new FileReader(); 158Please respect copyright.PENANAXPzPrGPcxF
reader.onload = () => 158Please respect copyright.PENANAkjdwtRZUpa
{158Please respect copyright.PENANA4jdBKVKjai
let content_whole = new Uint8Array(reader.result);158Please respect copyright.PENANAjtQ80OxEws
}158Please respect copyright.PENANAF66fIW1QM1
reader.readAsArrayBuffer(file);158Please respect copyright.PENANALwtoYgpZh8
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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:158Please respect copyright.PENANAWJSjWecPaF
---read part of file content into array buffer---158Please respect copyright.PENANAxDzA6uE6cc
let file=input.files[0], block_size=1000000, start=0, end=block_size; const reader = new FileReader(); 158Please respect copyright.PENANAQyZw5E6qdW
reader.onload = () => 158Please respect copyright.PENANAVcRVwmzfc7
{158Please respect copyright.PENANAtvcbcQO2Ka
let content_part = new Uint8Array(reader.result);158Please respect copyright.PENANARMQDYul7KL
}158Please respect copyright.PENANAUXSy3SLjdQ
reader.readAsArrayBuffer(file.slice(start,end));158Please respect copyright.PENANAhWk9PmXAc9
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158Please respect copyright.PENANAmD7Vlf5zTp
Section X. Thanks158Please respect copyright.PENANAkad0vIj5Yv
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]158Please respect copyright.PENANAG4kKg1pM6o
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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