How to set different page public url ?

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Now package.json homepage just one not more set ! I'm want just like :

    {
        "name": "index",
        "title": "index",
        "appHtml": "public/index.html",
        "appIndexJs": "src/index",
        "publicUrl":"/assert/index"  <- add this line to set different publicUrl 
    },

Thanks ~