Javascript (NodeJS) function to get the local IP from a network interface. (Uses windows default command line tool "ipconfig.exe" to get the local ip)

getNetworkAdapterIp.js

// Warning: undefined behaviour if the network interface does not have an IP (might fail or might return the next interface ip)

function getNetworkAdapterIp(adapter_name = "Adaptador de Rede sem Fio Wi-Fi", ip_version = 4, cp = require("child_process")) {
	process.stdout.setEncoding('utf-8');
	/** @type {Buffer} */
	const ipconfig_output = cp.spawnSync("C:\\Windows\\System32\\ipconfig.exe", ["/all"]).output[1];
	const adapter_config = ipconfig_output.toString("utf-8").split(adapter_name + ":")[1];
	if (!adapter_config) {
		return "ERROR - could not find adapter on output:\n" + (JSON.stringify(ipconfig_output.toString("utf-8")));
	} else {
		const ip_config = adapter_config.split("IPv" + ip_version + ". . . . . . . .  . . . . . . . :")[1];
		if (!ip_config) {
			return "ERROR - could not find ipv" + ip_version + " from adapter string:\n" + (JSON.stringify(adapter_config));
		} else {
			return (ip_config.split("\n")[0].split("(")[0].trim());
		}
	}
}

// JSON.stringify(getNetworkAdapterIp()) === "192.168.0.16"