So if you open up the inspector, you get this (if you're unlucky):
I'm building a tiny JS component which displays debugging information - is there any way to read the number of encountered errors and warnings so far?
A hacky solution I could come up with involves a bit of trickery by replacing the console.(error|log|warn) functions with my own, but I'm yet to test if it works for all cases (e.g. outside of code I own).
Is there a better way to do this?
As noted in this answer, it's generally not a good idea to change the behavior of native objects/methods. However, the following code should get you what you need in a fairly innocuous manner:
// Add this IIFE to your codebase:
(() => {
// Get all of the property names of the console:
const methodsToTrack = Object.keys(window.console);
// Create an object to collect total usage tallies in:
const usageRegistry = {};
for (let i = 0, j = methodsToTrack.length; i < j; i++) {
let methodName = methodsToTrack[i];
// If the property is not a method, don't touch it:
if(typeof window.console[methodName] !== 'function') {
continue;
}
// Cache the original console method here:
let consoleMethod = window.console[methodName];
// Overwrite console's method to increment the counter:
window.console[methodName] = function () {
// Defining registry properties here, so the registry only contains values for methods that were accessed:
usageRegistry[methodName] = usageRegistry[methodName] || 0;
// Execute the original method's behavior, capturing the returned value (if any) in a var, to return it at the end:
const returnedValue = consoleMethod(...arguments);
// Increment the usage registry for the executed method:
usageRegistry[methodName]++;
// Return the value the console's method would have returned, so the new method has the same signature as the old.
return returnedValue;
};
}
// Define a funciton to output the totals to a console log, then clean up after itself:
window.showConsoleTallies = function () {
window.console.log(usageRegistry);
usageRegistry['log']--;
}
})();
// Examples:
showConsoleTallies();
console.log('log 1');
console.error('error 1');
console.log('log 2');
console.warn('warn 1');
console.error('error 2');
console.log('log 3');
showConsoleTallies();PS: That's the ECMA6 version, but feel free to run it through Babel if you'd like it to be compiled for use in older browsers.
