javascript - 从 javascript 调用文本文件到变量时过滤行号

Question

我得到了这段代码，它将把 File.txt 的所有内容调用到变量 fileContent 中。我怎样才能让它只获取一个指定的行号而不是整个文件内容？

var xhr = new XMLHttpRequest();
xhr.open("GET","data/File.txt",false);
xhr.send(null);
var fileContent = xhr.responseText;

Answer 1

您可以按行结束字符拆分响应文本

// fileContent now  constain an array of strings
// where every item is a line
var fileContent = xhr.responseText.split('\n');
var lineNumber = 0;
var lineContent = fileContent[lineNumber]; // the content of the first line

// total number of lines
var linesCount = fileContent.length;

// random integer between 0 (minimum index) and linesCount - 1 (maximum index)
var randomLineNumber = Math.floor(Math.random() * linesCount);
var randomLineContent = fileContent[randomLineNumber];