This method can be used to send email template. Here we using nlapiLoadRecord() and nlapiCreateTemplateRenderer(). Below mentioned code for SuiteScript 1.0.
var emailTemplate = nlapiLoadRecord('emailtemplate', 444)
var emailBodys = emailTemplate.getFieldValue('content');
var renderer = nlapiCreateTemplateRenderer();
renderer.setTemplate(emailBodys);
var renderBody = renderer.renderToString();
var emailBodyfile = renderBody.replace("#firstname", data.name);
var emailBdy1 = emailBodyfile.replace("#lastname", data.lname);
var emailBdy2 = emailBdy1.replace("#email", data.email);
var emailBdy3 = emailBdy2.replace("#phone", data.phonenumber);
var emailBdy4 = emailBdy3.replace("#companyname", data.CompanyName);
var emailBdy5 = emailBdy4.replace("#message", data.message);
var emailBdy = emailBdy5;
console.log('embdy', emailBdy);
nlapiSendEmail(2436, emailid, 'Your contact has been Updated', emailBdy, null, null);In Email Template we using id (#firstname) for getting field values.
<html>
<title></title>
<p id=”firstname”>Dear #firstname #lastname</p>
<ul>
<li><strong>Email:</strong> #email</li>
<li><strong>Phone Number:</strong> #phone</li>
<li><strong>Company Name:</strong> #companyname</li>
<li><strong>Message:</strong> #message</li>
</ul>
</html>