防抖节流

function debounce(fn, interval = 300) {
    let timeout = null;
    return function () {
        clearTimeout(timeout);
        timeout = setTimeout(() => {
            fn.apply(this, arguments);
        }, interval);
    };
}

$('input.user-name').on('input', debounce(function () {
    $.ajax({
        url: `https://just.com/check`,
        method: 'post',
        data: {
            username: $(this).val(),
        },
        success(data) {
            if (data.isRegistered) {
                $('.tips').text('该用户名已被注册！');
            } else {
                $('.tips').text('恭喜！该用户名还未被注册！');
            }
        },
        error(error) {
            console.log(error);
        },
    });
}));

function throttle(fn, interval = 300) {
    let canRun = true;
    return function () {
        if (!canRun) return;
        canRun = false;
        setTimeout(() => {
            fn.apply(this, arguments);
            canRun = true;
        }, interval);
    };
}

$(window).on('scroll', throttle(function () {
    // 判断是否滚动到底部的逻辑
    let pageHeight = $('body').height(),
        scrollTop = $(window).scrollTop(),
        winHeight = $(window).height(),
        thresold = pageHeight - scrollTop - winHeight;
    if (thresold > -100 && thresold <= 20) {
        console.log('end');
    }
}));