npm install --save-dev webpack-dynamic-public-path

:warning: This plugin is compatible only with webpack 4.

webpack.config.js

const WebpackDynamicPublicPathPlugin = require("webpack-dynamic-public-path");

module.exports = {
    output: {
        publicPath: "publicPathPlaceholder",
    },
    plugins: [
        new WebpackDynamicPublicPathPlugin({
            externalPublicPath: "window.externalPublicPath"
        }),
    ]
}

bundle.js

// before
__webpack_require__.p = "publicPathPlaceholder";

// after
__webpack_require__.p = window.externalPublicPath;

new WebpackDynamicPublicPathPlugin(options: object)

|Name|Type|Description| |:--:|:--:|:----------| |externalPublicPath|{String}|JavaScript code, here you can define some variable or condition.| |chunkNames|{Array}|Chunk names in which publicPath will be replaced.|

chunkNames

In case if you have several entries you should define plugin instance for each of them. Check example.

webpack.config.js

const WebpackDynamicPublicPathPlugin = require("webpack-dynamic-public-path");

module.exports = {
    entry: {
        'index': path.resolve(__dirname, 'src', 'index.js'),
        'second-chunk': path.resolve(__dirname, 'src', 'second-chunk.js')
    },
    output: {
        filename: '[name].bundle.js',
        publicPath: "publicPathPlaceholder"
    },
    plugins: [
        new WebpackDynamicPublicPathPlugin({
            externalPublicPath: "window.externalPublicPathForMainChunk",
            chunkNames: ['index']
        }),
        new WebpackDynamicPublicPathPlugin({
            externalPublicPath: '"./"',
            chunkNames: ['second-chunk']
        }),
    ]
}

index.bundle.js

__webpack_require__.p = window.externalPublicPathForMainChunk;

second-chunk.bundle.js

__webpack_require__.p = "./";