Reader.md

ReaderOptions

• {String} encode - 文件编码，默认为utf8
• {Number} read_size - 总读取量，默认为file.size
• {Number} concurrency - 并发读取数，默认为1
• {Number} chunk_size - 每个分片大小，默认为1 << 16

BrowserFileReader(file, [options])

浏览器上的文件读取类，需要浏览器支持 FileReader 与 TypedArray 类

参数说明

• {File} file
• {ReaderOptions} [options]

Extends

• BaseReader

静态方法

• readAsText(): BrowserFileReader
• readAsArrayBuffer(): BrowserFileReader
• readAsDataURL(): BrowserFileReader
• read(): BrowserFileReader
• next(): BrowserFileReader
• slice(start, end): BrowserFileReader
• done(): boolean
• validate(record, sequence): boolean
• result(record, sequence): *
• isLastSnippet(record, sequence): boolean

Simple

import { BrowserFileReader } from 'next-reader'
const target = document.querySelector('#file')
target.onchange = () => {
  const file = target.files[0]
  const reader = new BrowserFileReader(file)
  reader.subscribe(
    (data, sequence) => console.log('onNext::', data, sequence),
    (error, already, read_size) => console.log('onError::', error, already, read_size),
    () => console.log('onCompleted')
  )
  reader.read()    // same as reader.readAsArrayBuffer()
  // or
  reader.readAsArrayBuffer()
  // or
  reader.readAsText()
  // or
  reader.readAsDataURL()
}

LineReaderOptions

Mixin ReaderOptions

• {Boolean} ignore_line_break - 输出结果是否忽略换行符，默认为true

ReadLineAsUint8(file, [options])

按行读取一个文件，输出结果为unsigned 8 bit类型

参数说明

• {File} file
• {LineReaderOptions} [options]

Extends

• BaseReader

静态方法

• read(): ReadLineAsUint8
• resume(): ReadLineAsUint8
• pause(): ReadLineAsUint8

静态属性

• Type
  • {String} line
  • {String} lines

Simple

import { ReadLineAsUint8 } from 'next-reader'
const Type = ReadLineAsUint8.Type
const target = document.querySelector('#file')
target.onchange = () => {
  const file = target.files[0]
  const reader = new ReadLineAsUint8(file)
  reader.subscribe(
    (record) => {
      const {type, no, size, data} = record   
      if (type === Type.lines) {
        console.log(data.forEach(d => console.log(d)))
      }else if (type ===Type.line) {
        console.log(data, no, size)
      }
    },
    (error, already, read_size) => console.log('onError::', error, already, read_size),
    () => console.log('onCompleted')
  )
  reader.read()
}

ReadLineAsString(file, [options])

参数说明

• {File} file
• {LineReaderOptions} [options]

Extends

• BaseReader

静态方法

• read(): ReadLineAsUint8
• resume(): ReadLineAsUint8
• pause(): ReadLineAsUint8

静态属性

• Type
  • {String} line
  • {String} lines

Simple 参考 ReadLineAsUint8 的example

ReadCsvAsUint8(file, [options])

参数说明

• {File} file
• {LineReaderOptions} [options]

Extends

• BaseReader

静态方法

• read(): ReadLineAsUint8
• resume(): ReadLineAsUint8
• pause(): ReadLineAsUint8

Simple

import { ReadCsvAsUint8 } from 'next-reader'
const target = document.querySelector('#file')
target.onchange = () => {
  const file = target.files[0]
  const reader = new ReadCsvAsUint8(file)
  reader.subscribe(
    (record) => {
      const { lines, size } = record
      lines.forEach(record => {
        console.log(record.fields, record.size, record.no)
      })
      console.log(size)
    },
    (error, already, read_size) => console.log('onError::', error, already, read_size),
    () => console.log('onCompleted')
  )
  reader.read()
}

ReadCsvWithLines(file, lines, [options])

从第一行开始，读取file指定lines行，输出结果为通过utf8解码后的string

参数说明

• {File} file
• {Number} lines - 需要读取多少行
• {LineReaderOptions} [options]

Extends

• BaseReader

静态方法

• read(): ReadLineAsUint8
• resume(): ReadLineAsUint8
• pause(): ReadLineAsUint8

Simple

import { ReadCsvWithLines } from 'next-reader'
const target = document.querySelector('#file')
target.onchange = () => {
  const file = target.files[0]
  const reader = new ReadCsvWithLines(file, 100)
  reader.subscribe(
    (record) => {
     const { lines, size } = record
       let total = 0
       lines.forEach(record => {
         console.log('No. %s: %s .%s', record.no, record.fields.toString(), record.size)
       })
       console.log('total => %s, size => %s', total, size)
    },
    (error, already, read_size) => console.log('onError::', error, already, read_size),
    () => console.log('onCompleted')
  )
  reader.read()
}