add variable to js from cli in webpack build

Question

I'm trying to add a variable to my app.js at the time of build. For example:

//app.js
var myvar = {{set_from_cli}};

then I want to run something like webpack -p --myvar='abc' which would result in this:

//bundle.js
var myvar = 'abc';

I've searched and maybe I'm just not looking in the right places or using the right terms, but can't figure out how to do this.

Westwick · Accepted Answer · 2016-05-26 22:53:15Z

1

You can access myvar at webpack.config.js like this (assuming minimist):

var argv = require('minimist')(process.argv.slice(2));
console.log(argv.myvar);

To get it to your bundle, you can use the DefinePlugin. You would need to have something like this at your plugin definition:

plugins: [
    new webpack.DefinePlugin({
      MYVAR: JSON.stringify(argv.myvar)
    })
]

Then at code

var myvar = MYVAR;

Adjust as necessary.

edited May 26, 2016 at 22:53

Westwick

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answered May 26, 2016 at 18:17

Juho Vepsäläinen

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2 Comments

Westwick Over a year ago

Thank for the reply, I added those first two codeblocks to my webpack.config.js but now when I try to run webpack -c tester I get: Error: Cannot resolve module 'tester'

Westwick Over a year ago

nevermind, had to add it at the right place (updated your example)

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