index.html

<html lang="ru">
<head>
    <title>PDF merger</title>
    <meta charset="UTF-8">
    <link rel="icon" href="document-icon.png">
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <link rel="stylesheet" href="css/styles.css">
</head>
<body>
<div id="root" @submit.prevent="sendFiles">
    <form id="form">
        <input
                id="file"
                type="file"
                name="documents"
                @change="getFiles"
                multiple accept="application/pdf"
        >

        <br>
        <input type="radio" id="pdf" value=".pdf" name="doctype" v-model="doctype" checked="checked">
        <label for="pdf">pdf</label>

        <br>
        <input id="filename" type="text" v-model="filename" name="filename">
        <label for="filename">Название файла</label>

        <br>
        <button type="submit">Отправить документы</button>
    </form>
    <div >
        <div v-for="file in respondedFiles">
            <a :href="`${file.serverName}`" :key="file.serverName" target="_blank">{{file.fileName}}</a>
            <br>
        </div>
    </div>
</div>

<script>
    new Vue({
        el: "#root",
        data: {
            files: [],
            doctype: '.pdf',
            filename: 'FOO',
            respondedFiles: [],
            allFiles: []
        },
        methods:{
            getFiles() {
                this.files = document.querySelector('#file').files
            },
            sendFiles() {
                const form = new FormData(document.querySelector('#form'))

                fetch('/api/sendFiles', {
                    method: "POST",
                    body: form,
                })
                .then(response=> {
                    if (response.ok) {
                        response.json().then(data => {
                            console.log(data)
                            this.respondedFiles.push(data)
                            console.log(this.respondedFiles)
                        })
                    } else {
                        alert('Файлы не загружены')
                    }
                })
            },
            getAllFiles() {
                fetch('/api/getFiles')
                .then(response=>{
                    if (response.ok) {
                        response.json()
                        .then(data=>{
                            this.allFiles = data
                        })
                    }
                })
            }
        }
    });
</script>

</body>
</html>