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    Convert errors to JSON or to a good string. Develop faster with better error messages.

    It's 2019 and still the default behavior of JavaScript could be better with regard to displaying/manipulating errors:

    • JSON.stringify(e): Bad
    • e.toString(): Bad
    • e.toJSON(): Doesn't exist
    • console.log(e): Bad in browsers, not so bad in Node but could be better

    But jsonify-error comes to the rescue:

    • For JSON.stringify(e):
      • Use JSON.stringify(jsonifyError(e)) instead
      • Or call jsonifyError.overrideErrorMethods() once and then JSON.stringify(e) will work.
    • For e.toString():
      • Use jsonifyError.asString(e) instead
      • Or call jsonifyError.overrideErrorMethods() once and then e.toString() will work.
    • For e.toJSON():
      • Use jsonifyError(e) instead
      • Or call jsonifyError.overrideErrorMethods() once and then e.toJSON() will work.
    • For console.log(e):
      • Use jsonifyError.log(e) instead
      • Or call jsonifyError.overrideConsole() once and then console.log(e) will work.


    In Browsers

    For browsers, simply include one of the dists in your entry point, such as dist/jsonify-error.js. The dists are available in jsDelivr:

    <script src="https://cdn.jsdelivr.net/npm/jsonify-error@2.0.0/dist/jsonify-error.min.js" integrity="sha384-k3Is8aV5PW6XO2NtZyFbjgZLKNWv4kFrtuN0cnOhaw+qKurzZIlOZZNmih+HGKpN" crossorigin="anonymous"></script>

    The following dists are available (with source maps):

    • dist/jsonify-error.js
    • dist/jsonify-error.min.js
    • dist/jsonify-error.es5.js
    • dist/jsonify-error.es5.min.js

    Or if you're developing a browser library with Browserify, you can just require it normally, as if you were in a Node environment.

    In Node

    In node, as usual, simply do:

    npm install --save jsonify-error


    The main purpose of jsonify-error, as the name suggests, is to convert an error to a plain object. Just do jsonifyError(e) and you will get something like:

        "name": "TypeError",
        "className": "TypeError",
        "message": "It can't be a string",
        "superclasses": ["Error", "Object"],
        "enumerableFields": {
            // If the error has other fields they appear here (including in the prototype chain):
            "someField": "someValue"
        "stack": [
            "TypeError: It can't be a string", 
            "at z (E:\\test.js:15:15)", 
            "at E:\\test.js:10:9", 
            "at Array.forEach (native)", 
            "at y (E:\\test.js:9:13)", 
            "at x (E:\\test.js:5:5)", 
            "at w (E:\\test.js:24:9)", 
            "at Object.<anonymous> (E:\\test.js:32:1)", 
            "at Module._compile (module.js:570:32)", 
            "at Object.Module._extensions..js (module.js:579:10)", 
            "at Module.load (module.js:487:32)"

    If you're thinking "Great! Now I can do console.log(jsonifyError(e)) instead of console.log(e)" in a browser, you're in the right track, but you can do even better! A few utility methods are exposed by jsonifyError beyond the main one, as mentioned in the beginning of this README.

    • jsonifyError.log(e): Logs the error in a much better way than console.log(e).
    • jsonifyError.overrideConsole(): Makes console.log, console.warn, console.error work like jsonifyError.log automatically. Calling this once is enough.
    • jsonifyError.overrideErrorMethods(): Heavily improves e.toString() and adds e.toJSON() to all errors automatically. Calling this once is enough.

    Example: with try-catch blocks

    const jsonifyError = require("jsonify-error");
    try {
        // ...
    } catch (e) {
        // ...

    Example: with promises

    const jsonifyError = require("jsonify-error");
    somethingAsync().then(() => {
        // ...
    }).catch(error => {
        // ...

    Also, for promises, there is a sibling module called better-promise-error-log which takes care of showing the improved logs automatically for unhandled rejections.

    Example: with express

    var jsonifyError = require("jsonify-error");
    app.get('/your/api', (req, res) => {
        // ...
        // Instead of res.status(500).json(error), do:

    Note: if you've overriden error methods (by calling jsonifyError.overrideErrorMethods()), the above can be simplified to res.status(500).json(error) (see the overriding methods section).

    Example usage: overriding methods

    const jsonifyError = require("jsonify-error");
    // Now `console.log`, `console.warn` and `console.error` will be much better.
    // Also, `e.toString()` will be much better and `e.toJSON()` will be available.


    Any contribution is very welcome. Feel free to open an issue about anything: questions, suggestions, feature requests, bugs, improvements, mistakes, whatever. I will be always looking.


    The changelog is available in CHANGELOG.md.

    See also


    MIT (c) Pedro Augusto de Paula Barbosa


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