Delete Multiple sites ECMA script -

DeleteSite: function () {

var count=siteUrlArray.length;

var i = 0;

for (i = 0; i < siteUrlArray.length; i++) {

var url = siteUrlArray[i];

var clientContext = new SP.ClientContext(url);

var oweb = clientContext.get_web();

oweb.deleteObject();
         
}
clientContext.executeQueryAsync(function () { alert("Total site deleted= "+count); }, function () { });


}
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Above functions shows how to delete multiple sites using ECMA Script. If any one is aware of bulk delete by JSOM using REST API plz do share.

Send Email using ecma script/JSOM / REST API - SharePoint

Below is the send email functionality based on SP.js As we can see below we have TO field commented out. Call 1: Sending to single user
var msg="html message to send";
buildContent.sendEmail("admin@test.com", "user@test.com" , msg, "Alert Notification!!");
in that case uncomment the line
// 'To': { 'results': [to] },
and comment the next line.

If we want to send to multiple users and SharePoint user Groups.

Call 2:
var to = [];
to.push("testUser1@test.com");
to.push("testUser2@test.com");
to.push("Site Owners");
var msg="html message to send";
buildContent.sendEmail("admin@test.com", to, msg, "Alert Notification!!");

sendEmail: function (from, to, body, subject) {
var siteurl = _spPageContextInfo.webServerRelativeUrl;
var urlTemplate = siteurl + "/_api/SP.Utilities.Utility.SendEmail";
        $.ajax({
            contentType: 'application/json',
            url: urlTemplate,
type: "POST",
            data: JSON.stringify({
'properties': { '__metadata': { 'type': 'SP.Utilities.EmailProperties' },
'From': from,
// 'To': { 'results': [to] },
'To': { 'results': to }, //
'Body': body, 'Subject': subject
                } } ),
            headers: { "Accept": "application/json;odata=verbose", "content-type": "application/json;odata=verbose", "X-RequestDigest": $("#__REQUESTDIGEST").val() }, success: function (data) { alert("Email send"); }, error: function (err) { alert(err.responseText);
// debugger;
} }); },

reference : http://blogs.msdn.com/b/spses/archive/2014/10/24/you-can-t-specify-the-from-address-for-email-messages-when-you-use-the-quot-send-an-email-quot-option-from-a-sharepoint-designer-2013-workflow-action.aspx