<button id="upload_widget" class="cloudinary-button">Upload files</button>

<script src="https://widget.cloudinary.com/v2.0/global/all.js" type="text/javascript"></script>  

<script type="text/javascript">  

    var myWidget = cloudinary.createUploadWidget({
        cloudName: '{{cloud_name}}',
        upload_preset: 'preset1',
        }, (error, result) => { if (result.event == "success") {
            console.log(result.info) // result.info contains data from upload
        } })

        document.getElementById("upload_widget").addEventListener("click", function(){
            myWidget.open();
        }, false);
    
</script>