documentit/node_modules/single-line-log/index.js

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1.3 KiB
JavaScript
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2018-01-05 18:48:13 +00:00
var MOVE_LEFT = new Buffer('1b5b3130303044', 'hex').toString();
var MOVE_UP = new Buffer('1b5b3141', 'hex').toString();
var CLEAR_LINE = new Buffer('1b5b304b', 'hex').toString();
var stringWidth = require('string-width');
module.exports = function(stream) {
var write = stream.write;
var str;
stream.write = function(data) {
if (str && data !== str) str = null;
return write.apply(this, arguments);
};
if (stream === process.stderr || stream === process.stdout) {
process.on('exit', function() {
if (str !== null) stream.write('');
});
}
var prevLineCount = 0;
var log = function() {
str = '';
var nextStr = Array.prototype.join.call(arguments, ' ');
// Clear screen
for (var i=0; i<prevLineCount; i++) {
str += MOVE_LEFT + CLEAR_LINE + (i < prevLineCount-1 ? MOVE_UP : '');
}
// Actual log output
str += nextStr;
stream.write(str);
// How many lines to remove on next clear screen
var prevLines = nextStr.split('\n');
prevLineCount = 0;
for (var i=0; i < prevLines.length; i++) {
prevLineCount += Math.ceil(stringWidth(prevLines[i]) / stream.columns) || 1;
}
};
log.clear = function() {
stream.write('');
};
return log;
};
module.exports.stdout = module.exports(process.stdout);
module.exports.stderr = module.exports(process.stderr);