hostBridgeBootstrapJs function

String hostBridgeBootstrapJs(String sendInvoke)

Builds the bootstrap installed into the JS engine.

sendInvoke is a JS expression evaluating to a function, called with the payload JSON string to ship a hostInvoke message to the host. It is parenthesised at the call site: a bare function (p) {...} in statement position parses as a declaration and is rejected for having no name. Everything else is identical across platforms.

Implementation

String hostBridgeBootstrapJs(String sendInvoke) =>
    '''
(function() {
  if (globalThis.__hostBridgeReady) return;
  globalThis.__hostBridgeReady = true;
  globalThis.__hostPending = {};
  globalThis.__hostNextUuid = 0;
  globalThis.host = {};
  globalThis.__hostResolve = function(uuid, jsonResult) {
    var p = globalThis.__hostPending[uuid];
    if (!p) return;
    delete globalThis.__hostPending[uuid];
    var v;
    try { v = JSON.parse(jsonResult); } catch (e) { v = null; }
    p.resolve(v);
  };
  globalThis.__hostReject = function(uuid, message) {
    var p = globalThis.__hostPending[uuid];
    if (!p) return;
    delete globalThis.__hostPending[uuid];
    p.reject(new Error(message));
  };
  globalThis.__hostCall = function(atom, verb, args) {
    var uuid = '_h' + (++globalThis.__hostNextUuid);
    return new Promise(function(resolve, reject) {
      globalThis.__hostPending[uuid] = { resolve: resolve, reject: reject };
      ($sendInvoke)(
        JSON.stringify({ uuid: uuid, atom: atom, verb: verb, args: args || [] }),
      );
    });
  };
})();
''';