Function createDebug

src/common.js:60–147

* Create a debugger with the given `namespace`. * * @param {String} namespace * @return {Function} * @api public

(namespace)

	* @api public
	*/
	function createDebug(namespace) {
		let prevTime;
		let enableOverride = null;
		let namespacesCache;
		let enabledCache;

		function debug(...args) {
			// Disabled?
			if (!debug.enabled) {
				return;
			}

			const self = debug;

			// Set `diff` timestamp
			const curr = Number(new Date());
			const ms = curr - (prevTime || curr);
			self.diff = ms;
			self.prev = prevTime;
			self.curr = curr;
			prevTime = curr;

			args[0] = createDebug.coerce(args[0]);

			if (typeof args[0] !== 'string') {
				// Anything else let's inspect with %O
				args.unshift('%O');
			}

			// Apply any `formatters` transformations
			let index = 0;
			args[0] = args[0].replace(/%([a-zA-Z%])/g, (match, format) => {
				// If we encounter an escaped % then don't increase the array index
				if (match === '%%') {
					return '%';
				}
				index++;
				const formatter = createDebug.formatters[format];
				if (typeof formatter === 'function') {
					const val = args[index];
					match = formatter.call(self, val);

					// Now we need to remove `args[index]` since it's inlined in the `format`
					args.splice(index, 1);
					index--;
				}
				return match;
			});

			// Apply env-specific formatting (colors, etc.)
			createDebug.formatArgs.call(self, args);

			const logFn = self.log || createDebug.log;
			logFn.apply(self, args);
		}

		debug.namespace = namespace;
		debug.useColors = createDebug.useColors();