Generate prepack input for xxx.

map_gen.js

var m = {}
Object.getOwnPropertyNames(window).filter(key => {
    let s = window[key] && window[key].toString()
    return !key.startsWith("_$") && s && s.indexOf("native code") != -1
}).map(key => {
    let fn = window[key]
    let ownKeys = [], protoKeys = []
    if (fn) {
        ownKeys = Object.getOwnPropertyNames(fn).filter(s => {
            if (s === "caller" || s === "callee" || s === "arguments" || s === "constructor") return false
            let result
            try {
                result = typeof fn[s] === "function" && !s.startsWith("__")
            } catch(err) {
                result = false
            }
            return result
        })
    }
    if (fn.prototype) {
        protoKeys = Object.getOwnPropertyNames(fn.prototype).filter(s => {
            if (s === "caller" || s === "callee" || s === "arguments" || s === "constructor") return false
            let result
            try {
                result = typeof fn.prototype[s] === "function" && !s.startsWith("__")
            } catch(err) {
                result = false
            }
            return result
        })
    }
    m[key] = fn
    ownKeys.map(s => {
        m[`${key}.${s}`] = fn[s]
    })
    protoKeys.map(s => {
        m[`${key}.prototype.${s}`] = fn.prototype[s]
    })
})
Object.getOwnPropertyNames(Math).map(key => {
    m[`Math.${key}`] = Math[key]
})

prepack_input_gen.js

var fixNativeMapping = {
  open: "XMLHttpRequest.prototype.open",
  submit: "HTMLFormElement.prototype.submit",
  Request: "Request",
  fetch: "fetch",
  clearInterval: "clearInterval"
};

Object.entries(window)
  .filter(e => e[0].startsWith("_$"))
  .map(e => {
    let [key, val] = e;
    // 1. undefined values
    if (!val) {
      // 1.1 empty string
      if (typeof val === "string" && val.length === 0) {
        return `var ${key} = ""`;
      }
      return `var ${key} = ${val}`;
    }
    let s = val.toString();

    // 2. object values
    if (s.startsWith("[object")) {
      if (val === window) {
        return `var ${key} = window`;
      } else if (val === document) {
        return `var ${key} = document`;
      } else if (val === JSON) {
        return `var ${key} = JSON`;
      } else if (val === Math) {
        return `var ${key} = Math`;
      } else {
        let result = {};
        Object.entries(val).map(e => {
          let [k, v] = e;
          if (!v || typeof v !== "function") {
            result[k] = v;
            return;
          }
          result[k] = v.toString();
        });
        return `var ${key} = ${JSON.stringify(result)}`;
      }
    }
    if (typeof val === "function") {
      let fn = val;
      let result;
      // 3. native functions
      if (s.indexOf("native code") !== -1) {
        let found = false;
        for (let k in m) {
          if (m[k] === fn) {
            result = k;
            found = true;
            break;
          }
        }
        if (!found) {
          let fixName = window[key].name;
          result = fixNativeMapping[fixName];
        }
      } else {
        // 4. user defined functions
        result = fn.toString();
      }
      return `var ${key} = ${result}`;
    }

    // 5. POD values
    // TODO: Location
    return `var ${key} = ${JSON.stringify(val)}`;
  })
  .join("\n");