tslint says calls to console.log are not allowed - How do I allow this?

Question

I just started using create-react-app with typescript

create-react-app my-app --scripts-version=react-scripts-ts

and the default tslint.json configuration does not allow console.log().

How can I (for now) enable console.log?

The docs for this are at https://palantir.github.io/tslint/rules/no-console/. But they don't say where to put this line:

    "no-console": [true, "log", "error"]

I searched and found this tslint.json configuration file syntax, so I tried this:

"rules": {
    "no-console": [true, "warning"]
}

In an attempt to get log messages that would just be warnings. But that didn't work.

I've commented out the few console.log() lines I have but will want to be able to do this in the future.

Cornellcornelle

Answer 1

Add // tslint:disable-next-line:no-console in the line right before your calls to console.log to prevent the error message only once.

If you want to disable the rule entirely add the following to your tslint.json (most likely in your root folder):

{
    "rules": {
        "no-console": false
    }
}

Codger

I'm not sure what happened but now "no-console": false is not working for me. I've found a work around is to put // tslint:disable:no-console at the top of the file. – Cornellcornelle

"no-console": false works for me, but I have to restart "npm start" for it to take effect. – Ruvolo

"no-console": false doesn't work for me, even with npm run start. – Vansickle

@EricFulmer put that in the "jsRules" node. "jsRules": { "no-console": false }, – Lope

I added the rule to jsRules and did a fresh yarn start before the errors went away. Not sure which one of those did it. – Browse

or in the same line as the following: console.log('hello world'); // tslint:disable-line:no-console – Spheroid

SYNTAX CHANGED. For the next-line exception there needs to be a space before no-console: // eslint-disable-next-line no-console. For the file exception, it also has to be inside of the Multi-line comment syntax: /* eslint-disable no-console */ – Kb

Answer 2

For those of you coming here with a mixed codebase of javascript and typescript.

You may need to define the 'no-console' option in jsRules, jslints rules object for javascript files, i.e. there are separate rules objects for javascript and typescript.

//tslint.json

{
  "extends": ["tslint:recommended", "tslint-react", "tslint-config-prettier"], //Example... 
  "rules": {
    "no-console": false //Disable for typescript
  },
  "jsRules": {
    "no-console": false //Disable for javascript
  }
}

Gale

but -- what is the purpose of this thing? – Midvictorian

Of jsRules, or no-console? – Gale

no-console -- it seems (I looked it up) that it is there only to warn you that console messages don't belong in production code. That kinda makes it a questionable rule any time your env is not prod – Midvictorian

I see your point, to a degree. One thing to consider is that console is not part of the javascript language, it's usually implemented in javascript engines, that's the point though - it's not part of the javascript language, you're baking a dependency into your code that may or may not exist. With that said, I can see a use for this rule. – Gale

@robertotomás, This rule is based on the best practice of not having console.log messages in your code. Production code should not have this, so this lets you know your not prod ready. You might have two tslint configurations one that allows it and another that does not. I have a logger.info function that calls console.log (so a wrapper) which allows me to easily enable or disable logging for the entire app. I'm not saying this is best practice, just something that I've done. It also makes it easier to integrate with another logger like github.com/krakenjs/beaver-logger. – Cornellcornelle

@robertotomás Years back when people still used IE a console.log() in your code would cause javascript to stop executing (crash) on that line. This is because IE treats console.log() as an error unless the developer tools are open. Of course, I don't know anyone who still use IE so these days it's just a matter of style/taste/opinion IMHO – Substituent

Answer 3

Add the following to your tslint.json

{
   "rules": {
      "no-console": {
         "severity": "warning",
      } 
   }
}

Wyman

Answer 4

This is the correct syntax to define the no-console rule (or any other rule for that matter) but only with a warning rather than an error (obviously change the options to whatever you want)

"no-console": {
    "severity": "warning",
    "options": [
        "log",
        "error",
        "debug",
        "info",
        "time",
        "timeEnd",
        "trace"
    ]
},

Album

This works perfectly as warning. BTW, this is not documented in tslint documentation. – Eminent

Answer 5

The way I handle tslint "no-console" rule is per file which I have found is convenient and isolated in the development phase.

As soon as I need to use the first console.log(); Visual Studio Code shows the option to add:

// tslint:disable-next-line: no-console

console.log();

So here I just delete "-next-line" and this command will cover the entire file.

// tslint:disable: no-console

console.log();

I hope it helps as an alternative to disable the feature for the entire app.

RON

Vizor

Answer 6

if // tslint:disable-next-line:no-console doesn't work try with // eslint:disable-next-line:no-console

Concoct

tslint:disable-next-line:no-console work well for me – Bernardinebernardo

Answer 7

Just a dirty hack to bypass linter:

const { log } = console; log('Hello linter'); // TODO: remove

Decoder

Answer 8

in typeScript version 3 update tslint.json under key rule like below:

"no-console": [
    true,
    "debug",
    "time",
    "timeEnd",
    "trace"
],

this way you just specify debug, time, timeEnd, trace to be not used, if in your default tslint "info" is in the list just remove it.

Psychometrics

This is the way it should be done as stated in the docs palantir.github.io/tslint/rules/no-console – Lacework

Answer 9

For those coming here looking for a way to keep console.log as disallowed, but to allow helpful methods like console.time and console.timeEnd, for example, you can explicitly define it globally in your .eslintrc rules:

 "no-console": ["error", {"allow": ["time", "timeEnd", "trace"]}],

Burnside

Answer 10

According to the docs: https://eslint.org/docs/user-guide/getting-started#configuration

• "off" or 0 - turn the rule off
• "warn" or 1 - turn the rule on as a warning (doesn’t affect exit code)
• "error" or 2 - turn the rule on as an error (exit code will be 1)

By the way, your correct setup would be

{
  "rules": {
    "no-console": false
  }
}

Saintmihiel

Answer 11

  {
    "extends": ["tslint:recommended", "tslint-react", "tslint-config-prettier"],
    "linterOptions": {
        "exclude": [
            "config/**/*.js",
            "node_modules/**/*.ts",
            "coverage/lcov-report/*.js"
        ]
    },
    "rules": {
        "no-console": false
    },
    "jsRules": {
        "no-console": false
    }
 }

Nevernever

Answer 12

The Syntax changed!

For the next-line exception there needs to be a space before no-console: // eslint-disable-next-line no-console.

For the file exception, it also has to be inside of the Multi-line comment syntax: /* eslint-disable no-console */.

It also might depend on certain configurations.

Kb