SharePoint Online Office 365 How to use Deferred and Promise in JavaScript Object Model to make asynchronous to synchronous call

Article
1/17/2024

Introduction:

Here we will discuss how we can use Deferred with when in JavaScript Object Model to make synchronous call in SharePoint Online or SharePoint 2016/2013. In SharePoint 2013 client object model supports ExecuteQueryAsync and not synchronous ExecuteQuery. When you call ExecuteQueryAsync in JSOM on the client side, it executes the object model code you declared and carries on immediately. But sometimes you may require doing a synchronous call.

We can use Deferred and promise in JavaScript Object Model in SharePoint 2013 to make call. Let us consider an example and then we will see how we can implement this.

Here let us take a list which has three columns:

Title
FirstName
LastName

And let us create an HTMLform where user can enter title, first name and last name and click on submit button to save the data in the list and once the data get saved it should display in a div. So in this situation, we need a synchronous call. Our Save to list code should execute first and once it is complete then our Retrieve list items code should execute which will fetch the data from list and show in a div.

Syntax:

var p = addListItem();
p.done(function(result) {
    retrieveListItems();
});
p.fail(function(result) {    
alert('error');
});

Here is you will see first addListItem() function will execute and once it is done then retrieveListItems() function will start execution.

Here the first function (addListItem())will return a promise like below:

function addListItem() {
    var d = $.Deferred();
  
    //Your code
  
    return d.promise();
}

In the success and failure method we can call the resolve() and reject() like below:

function onSuccess(d) {
    d.resolve();
}
 
function onFailure(d) {
    d.reject();
}

Full Code:

<h2>Add Items to Employee List</h2>
<div id="AddListData">
    <div>
        Title:
        <br />
        <input type="text" id="txtTitle" />
    </div>
    <div>
        First Name:
        <br />
        <input type="text" id="txtFirstName" />
    </div>
    <br />
    <div>
        Last Name:
        <br />
        <input type="text" id="txtLastName" />
    </div>
    <br />
    <div>
        <input id="btnSubmit" type="button" value="Submit" />
    </div>
</div>
<div id="divResult"></div>
<div id="divListItems"></div>

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>
<script>
var d = $.Deferred();
var listItemInfo = '';
$(function () {
    bindButtonClick();
});
 
function bindButtonClick() {
 
    $("#btnSubmit").on("click", function  () {     
    var p = addListItem();   
    p.done(function(result) {    
        retrieveListItems();
    });
    p.fail(function(result) {    
        alert('error');
    }); 
});
}
 
function addListItem() {
 
    var title = $("#txtTitle").val();
    var firstname = $("#txtFirstName").val();
    var lastname = $("#txtLastName").val();
    var clientContext = new SP.ClientContext();
    var oList = clientContext.get_web().get_lists().getByTitle('Employees');
    var itemCreateInfo = new SP.ListItemCreationInformation();
    this.oListItem = oList.addItem(itemCreateInfo);
    oListItem.set_item('Title', title);
    oListItem.set_item('FirstName', firstname);
    oListItem.set_item('LastName', lastname);
    oListItem.update();
    clientContext.load(oListItem);
    clientContext.executeQueryAsync(
    Function.createDelegate(this, this.onAddSucceeded),
    Function.createDelegate(this, this.onAddFailed)
    );
    return d.promise();
}
function onAddSucceeded(sender, args) {
    d.resolve(sender, args);
}
function onAddFailed(sender, args) {
    d.reject(sender, args); 
}
 
function retrieveListItems() {
    var clientContext = new SP.ClientContext();
    var oList = clientContext.get_web().get_lists().getByTitle('Employees');
    var camlQuery = new SP.CamlQuery();
    this.collListItem = oList.getItems(camlQuery);
    clientContext.load(collListItem);
    clientContext.executeQueryAsync(
    Function.createDelegate(this, this.onQuerySucceeded),
    Function.createDelegate(this, this.onQueryFailed)
    );  
}
function onQuerySucceeded(sender, args) {
    listItemInfo = '';
    var listItemEnumerator = collListItem.getEnumerator();
    while (listItemEnumerator.moveNext()) {
        var oListItem = listItemEnumerator.get_current();
        listItemInfo += '<strong>ID: </strong> '  + oListItem.get_id() +
        ' <strong>Title:</strong> ' + oListItem.get_item('Title') +
        ' <strong>FirstName:</strong> ' + oListItem.get_item('FirstName') +
        ' <strong>LastName:</strong> ' + oListItem.get_item('LastName') +
        '<br />';
    }
    $("#divListItems").html(listItemInfo);   
}
function onQueryFailed(sender, args) {
    alert('Hello');
}
 
</script>

Once you save the code and refresh the page, user can see a form. Let us enter the values in the field and click on Submit. It will show the list items like below:

https://www.enjoysharepoint.com/wp-content/uploads/2018/09/JavaScript_Object_Model_in_SharePoint_2013_synchronous_using_Deferred.png

References:

You can also read few useful articles below:

Conclusion:

Here we have discussed how to use Deferred and Promise in JavaScript Object Model in SharePoint 2013 to make asynchronous to synchronous call?

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