chunkhash

var path = require("path");
module.exports = {
    // mode: "development || "production",
    entry: {
        main: "./example"
    },
    optimization: {
        runtimeChunk: true
    },
    output: {
        path: path.join(__dirname, "dist"),
        filename: "[name].[chunkhash].js",
        chunkFilename: "[name].[chunkhash].js"
    }
};

webpack的runtime代码会在entry的chunk文件里，所以加上chunkhash并不能起到浏览器缓存的效果，因为每次打包即使entry代码没有变，chunkhash也是会变的。所以将webpack的runtime代码单独打包为一个文件即可解决。需要设置

optimization: {
    runtimeChunk: true
}

然后output里filename 和 chunkFilename加上[chunkhash] 。