function throttle(fn, threshhold, scope) { 
threshhold || (threshhold = 250); 
var last, 
timer; return function () { 
var context = scope || this; 
var now = +new Date(), 
args = arguments; 
if (last && now - last + threshhold < 0) { 
// hold on to it 
clearTimeout(deferTimer); 
timer = setTimeout(function () { 
last = now; 
fn.apply(context, args); 
}, threshhold); 
} else { 
last = now; 
fn.apply(context, args); 
} 
};}

$('body').on('mousemove', throttle(function (event) 
{
console.log('tick');
}, 1000));

function debounce(fn, delay) 
{ 
var timer = null; 
return function () 
{ 
var context = this,
args = arguments; 
clearTimeout(timer); 
timer = setTimeout(function () { 
fn.apply(context, args); 
}, delay); 
};}

$('input.username').keypress(debounce(function (event)
{
// do the Ajax request
}, 250));

/** * throttle * @param fn, wait, debounce */var throttle = function ( fn, wait, debounce ) { 
var timer = null, // 定时器 
t_last = null, // 上次设置的时间 
context, // 上下文 
args, // 参数 
diff; // 时间差 
return funciton () { 
var curr = + new Date(); 
var context = this, args = arguments; 
clearTimeout( timer ); 
if ( debounce ) { // 如果是debounce 
timer = setTimeout( function () { 
fn.apply( context, args ); 
}, wait ); 
} else { // 如果是throttle 
if ( !t_last ) t_last = curr; 
if ( curr - t_last >= wait ) { 
fn.apply( context, wait ); 
context = wait = null; 
} 
} }}/** * debounce * @param fn, wait */var debounce = function ( fn, wait ) 
{ 
return throttle( fn, wait, true );
}

_.throttle = function(func, wait, options) { 
var context, args, result; 
var timeout = null; 
// 定时器 
var previous = 0; 
// 上次触发的时间 
if (!options) options = {}; 
var later = function() { 
previous = options.leading === false "htmlcode">

_.debounce = function(func, wait, immediate) { 
// immediate默认为false 
var timeout, args, context, timestamp, result; 
var later = function() { 
// 当wait指定的时间间隔期间多次调用_.debounce返回的函数，则会不断更新timestamp的值，导致last < wait && last >= 0一直为true，从而不断启动新的计时器延时执行func var last = _.now() - timestamp; 
if (last < wait && last >= 0) { 
timeout = setTimeout(later, wait - last); 
} else { 
timeout = null; 
if (!immediate) { 
result = func.apply(context, args); 
if (!timeout) context = args = null; 
} 
} 
}; 
return function() 
{ 
context = this; 
args = arguments; 
timestamp = _.now(); 
// 第一次调用该方法时，且immediate为true，则调用func函数 
var callNow = immediate && !timeout; // 在wait指定的时间间隔内首次调用该方法，则启动计时器定时调用func函数 
if (!timeout) timeout = setTimeout(later, wait); 
if (callNow) { 
result = func.apply(context, args); 
context = args = null; 
} 
return result; 
};};


_.debounce实现的精彩之处我认为是通过递归启动计时器来代替通过调用clearTimeout来调整调用func函数的延时执行。
以上所述是小编给大家介绍的JavaScript性能优化之函数节流（throttle）与函数去抖（debounce），希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对网站的支持！