managewifi : function(success, fail) {
		cordova.exec(success, fail, 'WifiInfoPlugin', 'managewifi', [] );
}

var utils = require('cordova/utils'),
        exec = require('cordova/exec'),
        cordova = require('cordova');

WifiInfoPlugin.prototype.managewifi = function(success, fail) {
    exec(success, fail, 'WifiInfoPlugin', 'managewifi', []);
    alert('here');
};

Update WifiInfoPlugin.js