mirror of
https://github.com/debug-js/debug.git
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144 lines
3.0 KiB
JavaScript
144 lines
3.0 KiB
JavaScript
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/**
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* This is the web browser implementation of `debug()`.
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*
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* Expose `debug()` as the module.
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*/
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exports = module.exports = require('./debug');
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exports.log = log;
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exports.save = save;
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exports.load = load;
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/**
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* Colors.
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*/
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var colors = [
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'cyan',
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'green',
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'goldenrod', // "yellow" is just too bright on a white background...
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'blue',
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'purple',
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'red'
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];
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/**
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* Previously assigned color.
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*/
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var prevColor = 0;
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/**
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* Currently only WebKit-based Web Inspectors and the Firebug
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* extension (*not* the built-in Firefox web inpector) are
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* known to support "%c" CSS customizations.
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*
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* TODO: add a `localStorage` variable to explicitly enable/disable colors
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*/
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var useColors =
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// is webkit? http://stackoverflow.com/a/16459606/376773
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('WebkitAppearance' in document.documentElement.style) ||
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// is firebug? http://stackoverflow.com/a/398120/376773
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(window.console && (console.firebug || (console.exception && console.table)));
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/**
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* Map %j to `JSON.stringify()`, since no Web Inspectors do that by default.
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*/
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exports.formatters.j = function(v) {
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return JSON.stringify(v);
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};
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/**
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* Select a color.
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*
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* @return {Number}
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* @api private
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*/
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function selectColor() {
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return colors[prevColor++ % colors.length];
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}
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/**
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* Invokes `console.log()` when available.
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* No-op when `console.log` is not a "function".
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*
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* @api public
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*/
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function log() {
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var args = arguments;
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var curr = new Date();
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var ms = curr - (this.prev || curr);
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this.prev = curr;
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args[0] = (useColors ? '%c' : '')
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+ this.namespace
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+ (useColors ? '%c ' : ' ')
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+ args[0]
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+ (useColors ? '%c ' : ' ')
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+ '+' + exports.humanize(ms);
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if (useColors) {
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if (null == this.c) this.c = selectColor();
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var c = 'color: ' + this.c;
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args = [args[0], c, ''].concat(Array.prototype.slice.call(args, 1));
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// the final "%c" is somewhat tricky, because there could be other
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// arguments passed either before or after the %c, so we need to
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// figure out the correct index to insert the CSS into
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var index = 0;
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args[0].replace(/%[a-z%]/g, function(match) {
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if ('%%' === match) return;
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index++;
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if (index < 3) return; // skip the first 2 %c's since that's handled already
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if ('%c' === match) {
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args.splice(index, 0, c);
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}
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});
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}
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// This hackery is required for IE8,
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// where the `console.log` function doesn't have 'apply'
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return 'object' == typeof console
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&& 'function' == typeof console.log
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&& Function.prototype.apply.call(console.log, console, args);
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}
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/**
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* Save `namespaces`.
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*
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* @param {String} namespaces
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* @api private
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*/
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function save(namespaces) {
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try {
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localStorage.debug = namespaces;
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} catch(e) {}
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}
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/**
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* Load `namespaces`.
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*
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* @return {String} returns the previously persisted debug modes
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* @api private
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*/
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function load() {
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var r;
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try {
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r = localStorage.debug;
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} catch(e) {}
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return r;
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}
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/**
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* Enable namespaces listed in `localStorage.debug` initially.
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*/
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exports.enable(load());
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