Edit Word Document at client side and update back to server side appli

You can use the Document Editor to programatically open your Word documents, view, edit, and then save the changes to an output file which can be stored on your server.Here is some code that demonstrates this:
 

addImage = () => { // Load file
        //Allows the user to input an image of their choosing for the specific file types allowed at the cursor location 
        var input = document.createElement('input'); 
        input.type = 'file'; 
        input.style.display = 'none'; 
        input.accept = '.png, .docx, .doc, .jpg, .pdf'; 
        input.onchange = function (e) { 
            var files = input.files; 
            if (!files || !files.length) 
                return; 
            file = files[0]; 
            var url = URL.createObjectURL(file); 
            editor.engine.images.insertImage(url); 
        }; 
        input.click(); 
    }

    updateStyle = () => { //Edit something in the file
        //Allows the user to select from 3 different styling for the image they currently have selected 
        var value: number = null; 
        var input: string = prompt("Which image style would you like? (input the number corresponding to the style, default is Wrap Text)\n\n1. Inline\n2. Break Text\n3. Wrap Text"); 
        if (input == '1') { 
            value = 0; 
        } else if (input == '2') { 
            value = 1; 
        } else { 
            value = 2; 
        } 
 
        editor.engine.images.updateImageStyle(value); 
    }

exportAsDoc = () => { // Export changes to Docx file
        //exports the current document for saving 
        var promise = editor.document.toFile("untitled", lt.Document.Writer.DocumentFormat.Docx); 
        var err = null; 
        promise.then(function (name: string) { }); 
        promise.catch(function (err: string) { 
            alert("There was an issue exporting the document. " + err); 
        }); 
    } 

https://www.leadtools.com/help/sdk/v22/dh/javascript/de/imageengine.html
https://demo.leadtools.com/JavaScript/DocumentEditor/