index.html

<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>jsonTOthrift</title>
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bulma@0.8.0/css/bulma.min.css">
    <script defer src="https://use.fontawesome.com/releases/v5.3.1/js/all.js"></script>
</head>

<body>

    <section class="section">

        <div class="container">
            <h1 class="title">
                jsonTOthrift
            </h1>

            <h2>Json:</h2>
            <input id="name" class="input is-small" type="text" placeholder="Object name"> <br>
            <textarea id="obj" class="textarea is-small" placeholder="Json object" rows="15"></textarea>

            <br>
            <section>
                <button id="btn" class="button is-link is-light">Convert</button>
            </section>
            <br>

            <h2 class="title">
                Thrift object
            </h2>
            <section id="output" class="subtitle is-size-7">
            </section>
        </div>
    </section>
</body>

<script>
    const outerConvert = (name, obj) => {
        const array = new Map();
        convert(name, obj, array);
        return createStructs(array);
    }

    const convert = (name, obj, array) => {
        let t = typeof (obj);
        switch (t) {
            case "bigint":
                return typeV(name, 'i64');
            case "boolean":
                return typeV(name, 'bool');
            case "number":
                if (Number.isInteger(obj)) {
                    return typeV(name, 'i32');
                } else {
                    return typeV(name, 'double');
                }
            case "string":
                return typeV(name, 'string');
            case "object":
                if (Array.isArray(obj)) {
                    return typeV(name, `list<${convert(name + "Item", obj[0], array).t}>`)
                }
                let properties = [];
                for (const [key, value] of Object.entries(obj)) {
                    properties.push(convert(key, value, array))
                }

                let objV1 = objV(name, properties);
                array.set(objV1.name, objV1);
                return objV1;
        }
    };

    const typeV = (k, t) => {
        return ({
            name: k,
            t: t
        })
    }

    const objV = (k, vals) => {
        return ({
            name: capitalizeFirstLetter(k),
            vals: vals,
            t: 'MV' + capitalizeFirstLetter(k)
        });
    };

    const capitalizeFirstLetter = (string) => {
        return string.charAt(0).toUpperCase() + string.slice(1);
    };

    const createStruct = (struct) => {
        return `struct MV${struct.name} {\n${struct.vals.map((v, i) => `\t${i + 1}:${v.t} ${v.name}\n`).join('')}}\n`
    }

    const createStructs = (map) => {
        return Array.from(map.values()).map(createStruct).join('');
    }

    document.getElementById("btn").addEventListener("click", () => {
        const name = document.getElementById('name').value;
        const obj = document.getElementById('obj').value;
        const thriftObject = outerConvert(name, JSON.parse(obj));
        document.getElementById('output').innerText = thriftObject;
    });
</script>

</html>