How to set /auto populate Person/ Group field in SharePoint 2013 New/ edit forms using JavaScript?

Question

How to set /auto populate Person/ Group field in SharePoint 2013 New/ edit forms using Javascript? I tried this code and its not working in 2013

<script type="text/javascript">
//fiedName is the userfield displayName
//userName is the displayname of user you want to autofill
function SetUserFieldValue(fieldName, userName) {
        var _PeoplePicker = $("div[title='" + fieldName + "']"); //// $("[id$='ClientPeoplePicker'][title='" + fieldName + "']");  // not worked
        var _PeoplePickerTopId = _PeoplePicker.attr('id');
        var _PeoplePickerEditer = $("input[title='" + fieldName + "']");
        _PeoplePickerEditer.val(userName);
        var _PeoplePickerOject = SPClientPeoplePicker.SPClientPeoplePickerDict[_PeoplePickerTopId];
        _PeoplePickerOject.AddUnresolvedUserFromEditor(true);
    }
</script>

I can get the current logged in user, but struck to populate, resolve the user name in the person field.

Answer 1

Use JSLink on New and Edit form to set current user in people picker

    function setDefaultUser(ctx) {
        var currentUser = null;

        // Get the current form context
        var formCtx = SPClientTemplates.Utility.GetFormContextForCurrentField(ctx);

        // Get the current user
        $.ajax({
            async: false,
            headers: { "accept": "application/json; odata=verbose" },
            method: "GET",
            url: formCtx.webAttributes.WebUrl + "/_api/web/CurrentUser",
            success: function (data) {
                // Set the current user
                currentUser = data.d;
            }
        });

        // Ensure the current user exists
        if (currentUser != null) {
            var loginName = currentUser.LoginName.replace("\\", "\\\\");

            //Set user default value
            ctx.CurrentFieldValue = [{
                Description: loginName,
                DisplayText: currentUser.Title,
                EntityGroupName: "",
                EntityType: "",
                HierarchyIdentifier: null,
                IsResolved: true,
                Key: loginName,
                MultipleMatches: [],
                ProviderDisplayName: "",
                ProviderName: ""
            }];
        }

        // Return the html for the user field
        return SPClientPeoplePickerCSRTemplate(ctx);
    }

Answer 2

Following has been tested and worked in SharePoint 2013.

function SetUserFieldValue(fieldName, userName) {
    SP.SOD.executeFunc('sp.js', 'SP.ClientContext', function () {
        var _PeoplePicker = $("div[title='" + fieldName + "']");
        var _PeoplePickerTopId = _PeoplePicker.attr('id');
        var _PeoplePickerEditer = $("input[id$='EditorInput']");
        _PeoplePickerEditer.val(userName);
        var _PeoplePickerOject = SPClientPeoplePicker.SPClientPeoplePickerDict[_PeoplePickerTopId];
        _PeoplePickerOject.AddUnresolvedUserFromEditor(true);
    });
}