async run()

in web/src/wasm_exec.js [479:553]
64 lines of code
5 McCabe index (conditional complexity)

		async run(instance) {
			if (!(instance instanceof WebAssembly.Instance)) {
				throw new Error("Go.run: WebAssembly.Instance expected");
			}
			this._inst = instance;
			this.mem = new DataView(this._inst.exports.mem.buffer);
			this._values = [ // JS values that Go currently has references to, indexed by reference id
				NaN,
				0,
				null,
				true,
				false,
				globalThis,
				this,
			];
			this._goRefCounts = new Array(this._values.length).fill(Infinity); // number of references that Go has to a JS value, indexed by reference id
			this._ids = new Map([ // mapping from JS values to reference ids
				[0, 1],
				[null, 2],
				[true, 3],
				[false, 4],
				[globalThis, 5],
				[this, 6],
			]);
			this._idPool = [];   // unused ids that have been garbage collected
			this.exited = false; // whether the Go program has exited

			// Pass command line arguments and environment variables to WebAssembly by writing them to the linear memory.
			let offset = 4096;

			const strPtr = (str) => {
				const ptr = offset;
				const bytes = encoder.encode(str + "\0");
				new Uint8Array(this.mem.buffer, offset, bytes.length).set(bytes);
				offset += bytes.length;
				if (offset % 8 !== 0) {
					offset += 8 - (offset % 8);
				}
				return ptr;
			};

			const argc = this.argv.length;

			const argvPtrs = [];
			this.argv.forEach((arg) => {
				argvPtrs.push(strPtr(arg));
			});
			argvPtrs.push(0);

			const keys = Object.keys(this.env).sort();
			keys.forEach((key) => {
				argvPtrs.push(strPtr(`${key}=${this.env[key]}`));
			});
			argvPtrs.push(0);

			const argv = offset;
			argvPtrs.forEach((ptr) => {
				this.mem.setUint32(offset, ptr, true);
				this.mem.setUint32(offset + 4, 0, true);
				offset += 8;
			});

			// The linker guarantees global data starts from at least wasmMinDataAddr.
			// Keep in sync with cmd/link/internal/ld/data.go:wasmMinDataAddr.
			const wasmMinDataAddr = 4096 + 8192;
			if (offset >= wasmMinDataAddr) {
				throw new Error("total length of command line and environment variables exceeds limit");
			}

			this._inst.exports.run(argc, argv);
			if (this.exited) {
				this._resolveExitPromise();
			}
			await this._exitPromise;
		}