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Nacho Zve De La Torre
Asked: 2020-11-27 08:53:38 +0800 CST 2020-11-27 08:53:38 +0800 CST

Why does JSON.stringify() return an empty array?

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/* Validar checkboxes clickeados */
var checkboxes = document.querySelectorAll('.single-checkbox');
var clickeados = new Array();

checkboxes.forEach(elem => {
    elem.addEventListener('change', (event) => {
        event.stopPropagation();
        if(elem.checked) {
           if(!clickeados.includes(elem)){
                   clickeados.push(elem);
//                   console.log(clickeados);
           }
        }
        else{
            if(clickeados.includes(elem)){
                   clickeados.pop(elem);
//                   console.log(clickeados);
            }
        }
    });
});

/* Validar cuantos gustos fueron seleccionados antes de hacer el submit */
$('#vasitoForm').on('submit', (event) => {
    if(clickeados.length == 0){
        event.preventDefault();
        document.getElementById("errorGustos").innerHTML = "Debe seleccionar por lo menos un gusto";
    }
    else if(clickeados.length > 0 && clickeados.length < 3){
    console.log(clickeados);
        var myArray = JSON.stringify(clickeados);
//        $('#vasitoForm').attr('action', myArray + '/pedido');
        console.log(myArray);
    }
});

The console.log(clickeados) prints me the array of input's perfectly, but when I want to convert it to JSON and print it again the JSON comes out empty...

Array [ input.single-checkbox ] home.js:59:5

[{}] home.js:62:9

javascript

1 Answers

  1. Best Answer

    When JSON.stringifyit iterates your array to convert it to a string, it comes across the element input.single-checkboxwhich is an HTML node and it doesn't know how to convert it to a string, so it's left as an empty object.

    JSON.stringify([elem])
// "[{}]"

    I recommend that you instead build your own object with only the properties you use from the HTML node and that is what you convert viaJSON.stringify

    JSON.stringify([{props:1}])
// "[{"props":1}]"
    • 4