Categories
node.js

How to erase characters printed in console

I’ve been searching how to do it in other languages and I’ve found that I have to use the special character \b to remove the last character. (how-do-i-erase-printed-characters-in-a-console-applicationlinux)

This doesn’t work for node.js in multiple calls to console.log ();

If I write a single log:

console.log ("abc\bd");

I get the result: abd

But if I write:

console.log ("abc");
console.log ("\bd");

I get the result:

abc

d

My goal is to print a waiting message like:

Waiting

Waiting.

Waiting..

Waiting…

and again:

Waiting

Waiting.

etc

all in the same line.

There are functions available for process.stdout:

var i = 0;  // dots counter
setInterval(function() {
process.stdout.clearLine(); // clear current text
process.stdout.cursorTo(0); // move cursor to beginning of line
i = (i + 1) % 4;
var dots = new Array(i + 1).join(".");
process.stdout.write("Waiting" + dots); // write text
}, 300);

It is possible to provide arguments to clearLine(direction, callback)

/**
* -1 - to the left from cursor
* 0 - the entire line // default
* 1 - to the right from cursor
*/

Update Dec 13, 2015: although the above code works, it is no longer documented as part of process.stdin. It has moved to readline