设置jQuery Ajax全局beforeSend函数触发栈溢出错误求助

我想在jQuery Ajax配置里设置一个函数，让每次发起Ajax请求时自动执行它。我用了以下代码配置：

$.ajaxSetup({
    beforeSend: function(){
        validar_sesion();
    },
});

这是我发起Ajax请求的代码：

jQuery.ajax({
        url     : '...',
        data    : {...},
        method  : 'post',
        dataType:"json",
        }).then(resp=>{
              ....
        }).fail(resp=>{
            swal('请求出现问题，请联系管理员', {icon:'error'});
        }).catch(resp=>{
            console.log(resp.responseText);swal('请求出现问题，请联系管理员', {icon:'error'});
        });

需要自动执行的函数：

function validar_sesion(URL = '') {
    $.post(window.origin + '/login/verificar_iniciador', function(data) {
        if (data.length === 2) {
            location.reload();
        }
    });
}

执行时抛出错误：toast.js:221 Uncaught RangeError: Maximum call stack size exceeded，附上toast.js代码：

/**
 * --------------------------------------------------------------------------
 * Bootstrap (v4.5.0): toast.js
 * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
 * --------------------------------------------------------------------------
 */

import $ from 'jquery'
import Util from './util'

/**
 * ------------------------------------------------------------------------
 * Constants
 * ------------------------------------------------------------------------
 */

const NAME               = 'toast'
const VERSION            = '4.5.0'
const DATA_KEY           = 'bs.toast'
const EVENT_KEY          = `.${DATA_KEY}`
const JQUERY_NO_CONFLICT = $.fn[NAME]

const EVENT_CLICK_DISMISS = `click.dismiss${EVENT_KEY}`
const EVENT_HIDE          = `hide${EVENT_KEY}`
const EVENT_HIDDEN        = `hidden${EVENT_KEY}`
const EVENT_SHOW          = `show${EVENT_KEY}`
const EVENT_SHOWN         = `shown${EVENT_KEY}`

const CLASS_NAME_FADE    = 'fade'
const CLASS_NAME_HIDE    = 'hide'
const CLASS_NAME_SHOW    = 'show'
const CLASS_NAME_SHOWING = 'showing'

const DefaultType = {
  animation : 'boolean',
  autohide  : 'boolean',
  delay     : 'number'
}

const Default = {
  animation : true,
  autohide  : true,
  delay     : 500
}

const SELECTOR_DATA_DISMISS = '[data-dismiss="toast"]'

/**
 * ------------------------------------------------------------------------
 * Class Definition
 * ------------------------------------------------------------------------
 */

class Toast {
  constructor(element, config) {
    this._element = element
    this._config  = this._getConfig(config)
    this._timeout = null
    this._setListeners()
  }

  // Getters

  static get VERSION() {
    return VERSION
  }

  static get DefaultType() {
    return DefaultType
  }

  static get Default() {
    return Default
  }

  // Public

  show() {
    const showEvent = $.Event(EVENT_SHOW)

    $(this._element).trigger(showEvent)
    if (showEvent.isDefaultPrevented()) {
      return
    }

    if (this._config.animation) {
      this._element.classList.add(CLASS_NAME_FADE)
    }

    const complete = () => {
      this._element.classList.remove(CLASS_NAME_SHOWING)
      this._element.classList.add(CLASS_NAME_SHOW)

      $(this._element).trigger(EVENT_SHOWN)

      if (this._config.autohide) {
        this._timeout = setTimeout(() => {
          this.hide()
        }, this._config.delay)
      }
    }

    this._element.classList.remove(CLASS_NAME_HIDE)
    Util.reflow(this._element)
    this._element.classList.add(CLASS_NAME_SHOWING)
    if (this._config.animation) {
      const transitionDuration = Util.getTransitionDurationFromElement(this._element)

      $(this._element)
        .one(Util.TRANSITION_END, complete)
        .emulateTransitionEnd(transitionDuration)
    } else {
      complete()
    }
  }

  hide() {
    if (!this._element.classList.contains(CLASS_NAME_SHOW)) {
      return
    }

    const hideEvent = $.Event(EVENT_HIDE)

    $(this._element).trigger(hideEvent)
    if (hideEvent.isDefaultPrevented()) {
      return
    }

    this._close()
  }

  dispose() {
    clearTimeout(this._timeout)
    this._timeout = null

    if (this._element.classList.contains(CLASS_NAME_SHOW)) {
      this._element.classList.remove(CLASS_NAME_SHOW)
    }

    $(this._element).off(EVENT_CLICK_DISMISS)

    $.removeData(this._element, DATA_KEY)
    this._element = null
    this._config  = null
  }

  // Private

  _getConfig(config) {
    config = {
      ...Default,
      ...$(this._element).data(),
      ...typeof config === 'object' && config ? config : {}
    }

    Util.typeCheckConfig(
      NAME,
      config,
      this.constructor.DefaultType
    )

    return config
  }

  _setListeners() {
    $(this._element).on(EVENT_CLICK_DISMISS, SELECTOR_DATA_DISMISS, () => this.hide())
  }

  _close() {
    const complete = () => {
      this._element.classList.add(CLASS_NAME_HIDE)
      $(this._element).trigger(EVENT_HIDDEN)
    }

    this._element.classList.remove(CLASS_NAME_SHOW)
    if (this._config.animation) {
      const transitionDuration = Util.getTransitionDurationFromElement(this._element)

      $(this._element)
        .one(Util.TRANSITION_END, complete)
        .emulateTransitionEnd(transitionDuration)
    } else {
      complete()
    }
  }

  // Static

  static _jQueryInterface(config) {
    return this.each(function () {
      const $element = $(this)
      let data       = $element.data(DATA_KEY)
      const _config  = typeof config === 'object' && config

      if (!data) {
        data = new Toast(this, _config)
        $element.data(DATA_KEY, data)
      }

      if (typeof config === 'string') {
        if (typeof data[config] === 'undefined') {
          throw new TypeError(`No method named "${config}"`)
        }

        data[config](this)
      }
    })
  }
}

/**
 * ------------------------------------------------------------------------
 * jQuery
 * ------------------------------------------------------------------------
 */

$.fn[NAME]             = Toast._jQueryInterface
$.fn[NAME].Constructor = Toast
$.fn[NAME].noConflict  = () => {
  $.fn[NAME] = JQUERY_NO_CONFLICT
  return Toast._jQueryInterface
}

export default Toast

出现Maximum call stack size exceeded（栈溢出）的根本原因是无限递归：

• 你通过$.ajaxSetup给所有Ajax请求绑定了beforeSend钩子，每次发起Ajax都会先执行validar_sesion函数；
• 而validar_sesion内部又调用了$.post（这也是一个Ajax请求），触发beforeSend钩子再次调用validar_sesion；
• 如此循环往复，函数调用栈不断累积，最终超出浏览器的栈容量限制，抛出栈溢出错误。

需要让validar_sesion里的$.post请求跳过beforeSend钩子，避免触发递归。可以通过以下两种方式实现：

方案一：直接禁用当前请求的beforeSend钩子 #

修改validar_sesion函数，在$.post的配置里显式关闭全局钩子：

function validar_sesion(URL = '') {
    $.post({
        url: window.origin + '/login/verificar_iniciador',
        beforeSend: null, // 跳过全局的beforeSend钩子
        success: function(data) {
            if (data.length === 2) {
                location.reload();
            }
        }
    });
}

方案二：通过自定义标记排除特定请求 #

先修改全局ajaxSetup的钩子逻辑，判断请求是否包含自定义标记：

$.ajaxSetup({
    beforeSend: function(xhr, settings){
        // 如果请求带有skipBeforeSend标记，则跳过执行validar_sesion
        if (!settings.skipBeforeSend) {
            validar_sesion();
        }
    },
});

再修改validar_sesion里的请求，添加自定义标记：

function validar_sesion(URL = '') {
    $.post({
        url: window.origin + '/login/verificar_iniciador',
        skipBeforeSend: true, // 添加标记排除当前请求
        success: function(data) {
            if (data.length === 2) {
                location.reload();
            }
        }
    });
}

两种方案都能打破无限递归的循环，解决栈溢出问题。

内容的提问来源于stack exchange，提问作者Brayan Gonzalez