无论是否已添加，都会不断返回相同的警报消息。

Question

我正在尝试向用户提供反馈。如果他们已经添加了一些东西，他们会收到一条消息，说这个景点已经添加到您的行程中。如果用户的行程中没有景点，他们将收到成功消息。虽然它总是说这个景点已经被添加了，即使它还没有。没有错误，有谁知道为什么会这样。下面是该函数的代码。

function addAttractionItinerary(ev) {
 var id=$(ev.target).parents('div.Attraction')[0].$data.attraction_id;
$.post('php/validation.php', {"CHECKRECORD" :1 ,"id" : id}, function(data){
if (data = 1) {
alert("This attraction has already been added to your itinerary")
handleModalClose();
} else if  (data = 0){ 
         $.ajax({
    url: 'php/itinerary.php',
    type: 'POST', //will send a POST request to the PHP back-end with the "attractionId" the user has clicked on
    dataType: 'json',
    data: {
        action: 'CREATE',
        attractionId: $(ev.target).parents('div.Attraction')[0].$data.attraction_id //The $(ev.target).parents('div.attraction')[0].$data.attraction_id expression get's the "attractionId" of the clicked element
    },
    //It first get's the parent div with the class "attraction" reads the first one in the list [0] and then reads the $data property of this element
    success: function(data) {
 alert("The attraction is successfully added");
},
    error: console.log
}); 
    }
});
}

Answer 1

您应该使用if (data == 1) {} 和if (data == 0) {} 而不是if (data = 1) {}，因为这会将数据变量设置为1。

http://php.net/manual/en/control-structures.if.php http://php.net/manual/en/language.operators.comparison.php

Can I define a variable in a PHP if condition?

Answer 2

确保使用if(data == 0) 而不是if(data = 0)。一个= 将值赋给变量，而两个比较它们