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admin 2-Javascript, JQuery

When I was doing one of my projects , I needed a javascript function to read from a file and print it line by line.

However, it is not possible in Javascript to read from local file system.

Thus, I made a work around, which is to read from a file by PHP, and then append a line break symbol at the end of each line.

And finally, I have this javascript “class” to read from “file” line by line.

It works similar to BufferedReader in Java.

Here is the function:

String.prototype.trim = function () {
return this.replace(/^\s*/, "").replace(/\s*$/, "");
}

//line breaker %lb%
function FileReader(file) {
var lineBreaker ="%lb%";
this.fileString = file.trim();

var cursor = 0;
var recorder = new Array();

//public methods
this.close = function () {
cursor = 0;
recorder = null;
fileString ="";
}

this.readLine = function () {
var value = null;

if(cursor == 0 ){
process();
}

if(cursor<recorder.length) {
value = getLine();
cursor++;
}
alert(value);
return value;
}

//private methods
var process = function () {
recorder = fileString.split(lineBreaker);
}

var getLine = function() {
return recorder[cursor];
}

}

To use this “class”, firstly you can pass a file which is a String (formatted by backend language with a defined line break):

var fileObj = FileReader(file);

And when you call fileObj.readLine() , it will return a line of content.

Please notice that , you have to append a line break symbol(eg. %lb% ), you can also change the line break symbol ,but make

sure you change it in Javascript class.

admin General Javascript