下面的代码工作得很好。你需要通过id属性到达你的表单元素的输入更改:

var somethingChanged=false;
            $('#managerForm input').change(function() { 
                somethingChanged = true; 
           }); 
            $(window).bind('beforeunload', function(e){
                if(somethingChanged)
                    return "You made some changes and it's not saved?";
                else 
                    e=null; // i.e; if form state change show warning box, else don't show it.
            });
        });

通过jquery

$('#form').data('serialize',$('#form').serialize()); // On load save form current state

$(window).bind('beforeunload', function(e){
    if($('#form').serialize()!=$('#form').data('serialize'))return true;
    else e=null; // i.e; if form state change show warning box, else don't show it.
});

你可以谷歌JQuery表单序列化函数，这将收集所有表单输入并保存在数组中。我想这个解释就足够了:)

你可以在这里查看详细的解释: http://techinvestigations.redexp.in/comparison-of-form-values-on-load-and-before-close/

主要代码:

function formCompare(defaultValues, valuesOnClose) {
 
    // Create arrays of property names
    var aPropsFormLoad = Object.keys(defaultValues);
    var aPropsFormClose = Object.keys(valuesOnClose);
 
    // If number of properties is different,
    // objects are not equivalent
    if (aPropsFormLoad.length != aPropsFormClose.length) {
        return false;
    }
 
    for (var i = 0; i < aPropsFormLoad.length; i++) {
        var propName = aPropsFormLoad[i];
 
        // If values of same property are not equal,
        // objects are not equivalent
        if (defaultValues[aPropsFormLoad]+"" !== valuesOnClose[aPropsFormLoad]+"") {
            return false;
        }
    }
 
    // If we made it this far, objects
    // are considered equivalent
    return true;
 
}

//add polyfill for older browsers, as explained on the link above

//use the block below on load
    for(i=0; i < document.forms[0].elements.length; i++){
    console.log("The field name is: " + document.forms[0].elements[i].name +
        " and it’s value is: " + document.forms[0].elements[i].value );
    aPropsFormLoad[i] = document.forms[0].elements[i].value;
    }

//create a similar array on window unload event.

//and call the utility function
    if (!formCompare(aPropsOnLoad, aPropsOnClose))
    {
    //perform action: 
    //ask user for confirmation or
    //display message about changes made
    }

简短的回答:

let pageModified = true

window.addEventListener("beforeunload", 
  () => pageModified ? 'Close page without saving data?' : null
)

通用解决方案无需配置，自动检测所有输入修改，包括可满足的元素:

"use strict";
(() => {
const modified_inputs = new Set;
const defaultValue = "defaultValue";
// store default values
addEventListener("beforeinput", (evt) => {
    const target = evt.target;
    if (!(defaultValue in target || defaultValue in target.dataset)) {
        target.dataset[defaultValue] = ("" + (target.value || target.textContent)).trim();
    }
});
// detect input modifications
addEventListener("input", (evt) => {
    const target = evt.target;
    let original;
    if (defaultValue in target) {
        original = target[defaultValue];
    } else {
        original = target.dataset[defaultValue];
    }
    if (original !== ("" + (target.value || target.textContent)).trim()) {
        if (!modified_inputs.has(target)) {
            modified_inputs.add(target);
        }
    } else if (modified_inputs.has(target)) {
        modified_inputs.delete(target);
    }
});
// clear modified inputs upon form submission
addEventListener("submit", (evt) => {
    modified_inputs.clear();
    // to prevent the warning from happening, it is advisable
    // that you clear your form controls back to their default
    // state with evt.target.reset() or form.reset() after submission
});
// warn before closing if any inputs are modified
addEventListener("beforeunload", (evt) => {
    if (modified_inputs.size) {
        const unsaved_changes_warning = "Changes you made may not be saved.";
        evt.returnValue = unsaved_changes_warning;
        return unsaved_changes_warning;
    }
});
})();

您可以使用serialize()通过序列化表单值来创建URL编码的文本字符串，并检查表单在卸载前是否已更改

$(document).ready(function(){
    var form = $('#some-form'),
        original = form.serialize()

    form.submit(function(){
        window.onbeforeunload = null
    })

    window.onbeforeunload = function(){
        if (form.serialize() != original)
            return 'Are you sure you want to leave?'
    }
})

参考这个链接https://coderwall.com/p/gny70a/alert-when-leaving-page-with-unsaved-form 作者:弗拉基米尔·西多伦科