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console: add console.count() and console.clear()

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Both are simple utility functions defined by the WHATWG
console spec (https://console.spec.whatwg.org/).

PR-URL: https://github.com/nodejs/node/pull/12678
Ref: https://github.com/nodejs/node/issues/12675
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
This commit is contained in:
James M Snell 2017-04-26 12:42:18 -07:00
parent 98bae29304
commit cc43c8fb54
4 changed files with 194 additions and 0 deletions
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39
lib/console.js
View file

@ -23,6 +23,7 @@
const errors = require('internal/errors');
const util = require('util');
const kCounts = Symbol('counts');
function Console(stdout, stderr, ignoreErrors = true) {
if (!(this instanceof Console)) {
@ -55,6 +56,8 @@ function Console(stdout, stderr, ignoreErrors = true) {
prop.value = createWriteErrorHandler(stderr);
Object.defineProperty(this, '_stderrErrorHandler', prop);
this[kCounts] = new Map();
// bind the prototype functions to this Console instance
var keys = Object.keys(Console.prototype);
for (var v = 0; v < keys.length; v++) {
@ -166,6 +169,42 @@ Console.prototype.assert = function assert(expression, ...args) {
}
};
// Defined by: https://console.spec.whatwg.org/#clear
Console.prototype.clear = function clear() {
// It only makes sense to clear if _stdout is a TTY.
// Otherwise, do nothing.
if (this._stdout.isTTY) {
// The require is here intentionally to avoid readline being
// required too early when console is first loaded.
const { cursorTo, clearScreenDown } = require('readline');
cursorTo(this._stdout, 0, 0);
clearScreenDown(this._stdout);
}
};
// Defined by: https://console.spec.whatwg.org/#count
Console.prototype.count = function count(label = 'default') {
// Ensures that label is a string, and only things that can be
// coerced to strings. e.g. Symbol is not allowed
label = `${label}`;
const counts = this[kCounts];
let count = counts.get(label);
if (count === undefined)
count = 1;
else
count++;
counts.set(label, count);
this.log(`${label}: ${count}`);
};
// Not yet defined by the https://console.spec.whatwg.org, but
// proposed to be added and currently implemented by Edge. Having
// the ability to reset counters is important to help prevent
// the counter from being a memory leak.
Console.prototype.countReset = function countReset(label = 'default') {
const counts = this[kCounts];
counts.delete(`${label}`);
};
module.exports = new Console(process.stdout, process.stderr);
module.exports.Console = Console;