javascript - JSON: Uncaught TypeError: Cannot set property 'values' of undefined - Stack Overflow

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I am trying to pass the value of all the textareas on a page to a JSON table. For some reason I get a "cannot set value of undefined error", I dont understand since my Json is defined earlier.

Here is the code with the 2 functions.

function parseToJson() {
    var json = {};

    $("input.invoice_details").each(function () {
        json[this.id] = $(this).val();
    });

    $("select.invoice_details").each(function () {
        json[this.id] = $(this).val();
    });

    json.categories = {};

    $("textarea.invoice_categories").each(function () {
        if (this.value.trim() !== '') {
            json.categories[this.id].values = splitInput(this);
            json.categories[this.id].label = this.name;
        }
    });
    console.log(JSON.stringify(json));
    generatePreveiw(json);
}

function splitInput(textArea) {
    var input = textArea.value.trim();
    var lines = input.split("\n");
    var array = [];
    $.each(lines, function (indexLine, line) {
        var columns = line.split("\t");
        var obj = {};
        $.each(columns, function (indexColumn, column) {
            var columnName = columnsName.columnsName[indexColumn].name;
            obj[columnName] = column;
        });
        array.push(obj);
    });
    return array;
}

I am trying to pass the value of all the textareas on a page to a JSON table. For some reason I get a "cannot set value of undefined error", I dont understand since my Json is defined earlier.

Here is the code with the 2 functions.

function parseToJson() {
    var json = {};

    $("input.invoice_details").each(function () {
        json[this.id] = $(this).val();
    });

    $("select.invoice_details").each(function () {
        json[this.id] = $(this).val();
    });

    json.categories = {};

    $("textarea.invoice_categories").each(function () {
        if (this.value.trim() !== '') {
            json.categories[this.id].values = splitInput(this);
            json.categories[this.id].label = this.name;
        }
    });
    console.log(JSON.stringify(json));
    generatePreveiw(json);
}

function splitInput(textArea) {
    var input = textArea.value.trim();
    var lines = input.split("\n");
    var array = [];
    $.each(lines, function (indexLine, line) {
        var columns = line.split("\t");
        var obj = {};
        $.each(columns, function (indexColumn, column) {
            var columnName = columnsName.columnsName[indexColumn].name;
            obj[columnName] = column;
        });
        array.push(obj);
    });
    return array;
}

• javascript
• jquery
• json

Share Improve this question Follow edited Oct 21, 2015 at 9:45 Rory McCrossan 338k4141 gold badges320320 silver badges351351 bronze badges asked Oct 21, 2015 at 9:32 0xtuytuy0xtuytuy 1,65477 gold badges2929 silver badges5656 bronze badges 4

• Which line throws the error? – JJJ Commented Oct 21, 2015 at 9:36
• json.categories[this.id].values = splitInput(this); – 0xtuytuy Commented Oct 21, 2015 at 9:42
• Please show your json data – Jibin Mathew Commented Oct 21, 2015 at 9:47
• 1 var json = {}; — That isn't JSON. That is a JavaScript object. JSON is an external data format that happens to be inspired by JavaScript literal syntax. – Quentin Commented Oct 21, 2015 at 9:48

Add a ment  | 

3 Answers 3

Sorted by: Reset to default 4

        json.categories[this.id].values = splitInput(this);
        json.categories[this.id].label = this.name;

should be:

        json.categories[this.id] = {
            values: splitInput(this),
            label: this.name
        };

You can't set the properties of an object when you haven't created the object first. You can use this object literal syntax to create the object and its properties in one step.

json.categories = {};

You have an empty object

json.categories[this.id].values = splitInput(this);

Now you are trying to access a property called this.id from that object.

Since the object doesn't have any properties yet, that will always be undefined

You then try to assign undefined.value = splitInput(this), which throws an error.

You need to make sure json.categories[this.id] has a value before you can set properties on it.

The problem is that you are trying to access a property of the object stored in json.categories[this.id]. Unfortunately it is undefined. Try the following:

function() {
        if (this.value.trim() !== '')
        { 
            //Initialize to an empty object if necessary
            json.categories[this.id] = json.categories[this.id] || {};
            json.categories[this.id].values = splitInput(this);
            json.categories[this.id].label = this.name;
        }
    });

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