JSON.parse获取值

I need to check one value from JSON response before continuing the script, but it doesn't work.

$.ajax({
    type: "POST",
    url: "addproduct.php",
    data: {productId : selectedValue, customerId : customerId},
    datatype: "json",
    success: function (response) {
        response = JSON.parse(response);
        if(response === undefined) {
            alert("undefined");
        } else if (response.pricelistupdate = 1) { //this doesn't work
            alert("ERROR! Adding a product is denied");
        } else {
            orderAddRow(response);
        }
    },
    error: function () {
        alert("ERROR");
    }
});

I'm getting following JSON response:

{"row":{"pricelistupdate":0,"ID":"000017","name":"Chair","discount":"0.00","price":"0.00"}}

Thanks in advance.

What errors did i see:

1. You don't need the JSON.parse() as datatype:"json" is there.
2. Reference to the pricelistupdate should be response.row.pricelistupdate.
3. Instead of comparing === to a value you are assigning it = in the elseif.

As you have a dataType:

datatype: "json",

so you don't need to parse the json then. you can remove it response = JSON.parse(response);.

JSON.parse() method should only be used on a json string but in your case the response is a valid json so you don't need it.

and just get it:

You need to refer to your object keys and you are missing the key row and you have also missed = equal sign in the elseif :

else if (response.row.pricelistupdate === 1) 

So it has to be something like this in your success callback:

success: function (response) {
    if(response === undefined) {
        alert("undefined");
    } else if (response.row.pricelistupdate === 1) { // check "===" equals
        alert("ERROR! Adding a product is denied");
    } else {
        orderAddRow(response);
    }
},

@jai is right since your response type is json so your "response" variable is already contains json so first of all remove

 response = JSON.parse(response);

seeing at your response, your response is stored in row object so you are accessing "pricelistupdate" incorrectly you should replace it with response.row.pricelistupdate so your final code looks like

$.ajax({
    type: "POST",
    url: "addproduct.php",
    data: {productId : selectedValue, customerId : customerId},
    datatype: "json",
    success: function (response) {
        if(response === undefined) {
            alert("undefined");
        } else if (response.row.pricelistupdate = 1) { 
            alert("ERROR! Adding a product is denied");
        } else {
            orderAddRow(response.row);
        }
    },
    error: function () {
        alert("ERROR");
    }
});