mattbierner / tonsole

Node.js wrapper around console.log that add return values

Tonsole

Wrapper around Node's console that adds return values to logging calls.

This is useful for logging expressions and arrow functions without having to change any code.

const tonsole = require('tonsole');

let compute = (data) => data ? process(data.value) : data;

// Normally we can't easily log what `compute` does without
// rewriting it to use statements
compute = (data) => {
    if (data) {
        const r = process(data.value);
        console.log('Processed data: ', r);
        return r;
    }
    console.error('Invalid data: ', data);
    return data;
};

// But with tonsole, we can add logging while still using
// expressions, just as the ancient ones of Lisp intended.
compute = (data) =>
    data
        ?tonsole.log('Processed data: ', process(data.value))
        :tonsole.error('Invalid data: ', data);

Usage

$ npm install --save tonsole

Tonsole provides a complete wrapper around the entire Node console api. All functions forward to the wrapped Node console implementation.

tonsole.Console(stdout [, stderr])

Wrapper around console.Console. Logging methods of this class return values besides logging.

tonsole.log(...args)

tonsole.info(...args)

tonsole.warn(...args)

tonsole.error(...args)

Each of these methods logs using the inner console.* method, but instead of returning undefined, they return the last argument value.

tonsole.log("%s : %s", 2, 3);
// Logs: "2 : 3"
// returns 3

tonsole.assert(value, ...args)

Verify that value is truthy using console.assert but returns value. If value is falsy, an AssertionError is thrown.

tonsole.assert(5, "sanity check") === 5

tonsole.assert(false, "should fail") // throws AssertionError 

tonsole.dir(obj, options)

Simply wrapper around console.dir that returns obj.

tonsole.time(label)

tonsole.timeEnd(label)

tonsole.trace(msg, ...)

Forward directly to console.* and continue to return undefined.