js节流函数

function throttle(func, wait) {
var context, args;
var previous = 0;

return function() {
    var now = +new Date();
    context = this;
    args = arguments;
    if (now - previous > wait) {
        func.apply(context, args);
        previous = now;
    }
}

}

function throttle(func, wait) {
var timeout;
var previous = 0;

return function() {
    context = this;
    args = arguments;
    if (!timeout) {
        timeout = setTimeout(function(){
            timeout = null;
            func.apply(context, args)
        }, wait)
    }

}

}