[英]Node.js Readline, get the current line number
我有以下实现,除了这一行,一切正常:
lineNumber: line.lineNumber
此行返回未定义,我在下面添加了完整的代码片段,我的问题是:Readline 是否提供了以某种方式获取行号的标准方法? 或者我必须实现我的计数器来跟踪行号,这很简单,但我不想要这样做的标准方法吗?
/**
* Search for occurrences of the specified pattern in the received list of files.
* @param filesToSearch - the list of files to search for the pattern
* @returns {Promise} - resolves with the information about the encountered matches for the pattern specified.
*/
const findPattern = (filesToSearch) => {
console.log(filesToSearch);
return new Promise((resolve, reject) => {
var results = [ ];
// iterate over the files
for(let theFile of filesToSearch){
let dataStream = fs.createReadStream(theFile);
let lineReader = readLine.createInterface({
input: dataStream
});
let count = 0; // this would do the trick but I'd rather use standard approach if there's one
// iterates over each line of the current file
lineReader.on('line',(line) => {
count++;
if(line.indexOf(searchPattern) > 0) {
let currLine = line.toString();
currLine = currLine.replace(/{/g, '');//cleanup { from string if present
results.push({
fileName: theFile,
value: currLine,
lineNumber: line.lineNumber //HERE: this results undefined
//lineNumber: count // this does the trick but I'd rather use standard approach.
});
}
});
// resolve the promise once the file scan is finished.
lineReader.on('close', () => resolve(results));
}
});
};
不幸的是,没有办法使用readline
节点模块找到行号,但是,使用 ES6 在一行代码中滚动你自己的计数器并不困难。
const line_counter = ((i = 0) => () => ++i)();
当我们创建回调函数时,我们只是将第二个参数默认为line_counter
函数,我们可以表现得好像行和行号都line
事件发生时被传递。
rl.on("line", (line, lineno = line_counter()) => {
console.log(lineno); //1...2...3...10...100...etc
});
简单地说,将变量增量与 foo(data, ++i) 一起使用,它将始终将新行的编号传递给函数。
let i = 0
const stream = fs.createReadStream(yourFileName)
stream.pipe().on("data", (data) => foo(data, ++i))
const foo = (data, line) => {
consle.log("Data: ", data)
consle.log("Line number:", line)
}
如果您使用节点 linereader,则需要包含 lineno 参数
lineReader.on('line', function (lineno, line) {
if(line.indexOf(searchPattern) > 0) {
let currLine = line.toString();
currLine = currLine.replace(/{/g, '');//cleanup { from string if present
results.push({
fileName: theFile,
value: currLine,
lineNumber: lineno
});
}
});
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