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April 27, 2016 12:02
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Attempt to wrap the `console.log()` method of the browser and successfully bind to the client object calling `logger.debug()` and not the logger itself.
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// I've created a simple logger (wraps console.* methods) that provides output similar to say Log4J or other robust | |
// loggers out there for the enterprise, but a huge missing piece (for me) is that you can no longer see the file | |
// reference and line number from the client object using the logger. When you use console.log() OOTB it'll spit out | |
// a clickable link to the file and line number that executed the console.log making it easy to debug; when you wrap | |
// console.log it simply spits out the logger file reference and the line number the console.log was executed, so | |
// all logging shows up as from the logger wrapper (which is technically correct)...bottom line, you lose the context | |
// from which you actually made the logging call and I'd like to get that back. | |
// Aside from blackboxing, is there another way to wrap console.log() such that it binds to the client callee | |
// and ultimately shows the correct file reference and line number of the callee (and not the log wrapper)? | |
// @JohnYanarella pointed me to the blackboxing solution for Chrome Dev Tools via Paul Irish | |
// http://bl.ocks.org/paulirish/c307a5a585ddbcc17242, but I'm looking for a code-only solution...possible? | |
// `console.log.bind` is used as an attempt to force the client calling `logger.debug()` to save | |
// the correct line numbers and file so it shows up correctly in Chrome Dev Tools' console and not as | |
// those of the logger itself. | |
var logFactory = | |
{ | |
// Correctly displays the client object filename and line number that called debug(), | |
// but we can't manipulate the input. | |
getLoggerA: function () { | |
return { | |
// I want to intercept the args being passed to debug() from the | |
// client object calling so I can further manipulate the actual log | |
// and not hardcode to say "MAGIC"...so in the example below, how do we | |
// capture the incoming "BMR" and change it to "BMR, TJM, AG"? | |
debug: console.log.bind(console, 'MAGIC') | |
}; | |
}, | |
// DOES NOT correctly display the client object filename and line number that called debug() | |
// and shows the logger itself, but does allow us to capture the input... | |
getLoggerB: function () { | |
return { | |
debug: (function () { | |
var logFn = console.log.bind(console); | |
return function (msg) { | |
logFn("PREFIX ", msg); | |
}; | |
})() | |
}; | |
}, | |
// DOES NOT correctly display the client object filename and line number that called debug() | |
// and shows the logger itself, but does allow us to capture the input... | |
getLoggerC: function (context) { | |
var Logger = function(context) | |
{ | |
this.context = context || "DEFAULT CONTEXT"; | |
this.logFn = console.log.bind(console); | |
this.debug = function(msg) { | |
this.logFn(this.context, msg); | |
} | |
}; | |
return new Logger(context); | |
} | |
}; | |
logFactory.getLoggerA().debug("BMR"); // output >> "MAGIC BMR" with correct line numbers and file ref | |
logFactory.getLoggerB().debug("BMR"); // output >> "PREFIX BMR" with incorrect line numbers and file ref | |
logFactory.getLoggerC().debug("BMR"); // output >> "DEFAULT CONTEXT BMR" with incorrect line numbers and file ref |
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And sorry for the delayed response @ThomasBurleson as I didn't realize gists no longer notify you when someone comments: isaacs/github#21