Two ways to write throttling - recently seen

The first one is

        function throttle(fn, delay) {
    
            let timer = 0
            return function (fn, delay) {
    
                if (timer) {
    
                    return false
                }
                timer = setTimeout(() => {
    
                    fn.apply(this, arguments)
                    timer = 0
                }, delay)
            }
        }

The second kind

   function throttle(fn, delay) {
    
            let flag = true
            return function (fn, delay) {
    
                if (!flag) {
    
                    return false
                }
                flag = false
                setTimeout(() => {
    
                   fn.apply(this, arguments)
                    flag = true
                }, delay)
            }
        }

summary ： Two ways of writing , In fact, the effect is a kind of , The first method is simpler in code . It's just if The judgment has changed