求教，定义了全局变量，后面函数为什么一直赋值不会变呢？

var STATE_IDLE = 0;
var STATE_LONG = 1;
var STATE_SHORT = 2;
var State = STATE_IDLE;

function Trade(currentState, nextState) {

    if (currentState === STATE_IDLE) {
        if (nextState === STATE_LONG) {
            exchange.SetDirection("buy");
            AmountOP = InitAccount.Stocks * 10 / 2;
            exchange.Buy(_C(exchange.GetTicker).Sell, AmountOP);
            State = STATE_LONG;
        }

后面还有其他条件判断执行，也会更改State的值，但为什么一直是0，不会变呢？