In javascript, how to trigger event when a variable's value is changed? [duplicate]

Answer 1

The most reliable way is to use setters like that:

var trafficLightIsGreen = false; 
var someoneIsRunningTheLight = false;

var setTrafficLightIsGreen = function(val){
    trafficLightIsGreen = val;
    if (trafficLightIsGreen and !someoneIsRunningTheLight){
        go(); 
    };
};
var setSomeoneIsRunningTheLight = function(val){
    trafficLightIsGreen = val;
    if (trafficLightIsGreen and !someoneIsRunningTheLight){
        go(); 
    };
};

and then instead of assigning a value to a variable, you just invoke the setter:

setTrafficLightIsGreen(true);