Is there a method for printing to the console without a trailing newline? The console
object documentation doesn't say anything regarding that:
console.log()
Prints to stdout with newline. This function can take multiple arguments in a
printf()
-like way. Example:console.log('count: %d', count);
If formating elements are not found in the first string then
util.inspect
is used on each argument.
转载于:https://stackoverflow.com/questions/6157497/node-js-printing-to-console-without-a-trailing-newline
Also, if you want to overwrite messages in the same line, for instance in a countdown, you could add '\r' at the end of the string.
process.stdout.write("Downloading " + data.length + " bytes\r");
util.print can be used also. Read: http://nodejs.org/api/util.html#util_util_print
util.print([...])# A synchronous output function. Will block the process, cast each argument to a string then output to stdout. Does not place newlines after each argument.
An example:
// get total length
var len = parseInt(response.headers['content-length'], 10);
var cur = 0;
// handle the response
response.on('data', function(chunk) {
cur += chunk.length;
util.print("Downloading " + (100.0 * cur / len).toFixed(2) + "% " + cur + " bytes\r");
});
In Windows console (Linux, too), you should replace '\r' with its equivalent code \033[0G:
process.stdout.write('ok\033[0G');
This uses a VT220 terminal escape sequence to send the cursor to the first column.
None of these solutions work for me. process.stdout.write('ok\033[0G') and just using '\r' just create a new line, do not overwrite, Mac OSX 10.9.2
EDIT: I had to use this to replace the current line
process.stdout.write('\033[0G'); process.stdout.write('newstuff');
I got an error when using strict mode.
Node error: "Octal literals are not allowed in strict mode."
I found the answer here: https://github.com/SBoudrias/Inquirer.js/issues/111
process.stdout.write("received: " + bytesReceived + "\x1B[0G");
There seem to be many answers suggesting process.stdout.write
. Error logs should be emitted on process.stderr
instead (Use console.error
). For anyone who is wonder why process.stdout.write('\033[0G'); wasn't doing anything it's because stdout is buffered and you need to wait for drain
event (See Stdout flush for NodeJS?). If write returns false it will fire a drain
event.
As an expansion/enhancement to the brilliant addition made by @rodowi above regarding being able to overwrite a row:
process.stdout.write("Downloading " + data.length + " bytes\r");
Should you not want the terminal cursor to be located at the first character, as I saw in my code, the consider doing the following:
let dots = ''
process.stdout.write(`Loading `)
let tmrID = setInterval(() => {
dots += '.'
process.stdout.write(`\rLoading ${dots}`)
}, 1000)
setTimeout(() => {
clearInterval(tmrID)
console.log(`\rLoaded in [3500 ms]`)
}, 3500)
By placing the \r
in front of the next print statement the cursor is reset just before the replacing string overwrites the previous.