Platform vs Core

The two library layers in SSJS — Platform.Function.* vs Core library objects — and when to use each.

Claims checked Test scripts included

SSJS exposes SFMC functionality through two distinct library layers with different usage patterns, capabilities, and performance characteristics.

The Two Layers

SSJS Runtime
├── Platform             (always available, no Load required)
│   ├── Platform.Function.*    (~55 methods)
│   ├── Platform.Variable.*    (AMPscript bridge)
│   ├── Platform.Response.*    (HTTP response)
│   ├── Platform.Request.*     (HTTP request)
│   ├── Platform.Recipient.*
│   └── WSProxy
└── Core library         (requires Platform.Load("core", "1.1.5"))
    ├── DataExtension, DataExtension.Rows, DataExtension.Fields
    ├── Subscriber, Email, TriggeredSend
    ├── List, List.Subscribers
    ├── Send, Template, ContentArea, Folder
    ├── QueryDefinition, FilterDefinition, SendDefinition
    ├── Account, AccountUser, Portfolio
    └── BounceEvent, ClickEvent, OpenEvent, … (tracking events)

Show test script

<script runat="server">
/*
 * Chapter: The Two Layers
 * Proves:
 *   1. Platform available; bare DataExtension undefined before Load.
 * EXPECTED OUTPUT: every line starts with PASS.
 */
function assert(id, actual, expected) {
    Platform.Response.Write((actual === expected ? "PASS " : "FAIL ") + id + " -> [" + actual + "]\n");
}
function typeOfThunk(fn) {
    try { return "" + fn(); } catch (ex) { return "THREW:" + ("" + ex.message); }
}
assert("Platform typeof", typeof Platform, "clr");
assert("DataExtension before Load", typeOfThunk(function () { return typeof DataExtension; }), "undefined");
</script>

Platform Functions

Available without any loading. Call directly as Platform.Function.MethodName(...).

Best for:

• Data Extension lookups and writes in CloudPages and emails
• String/date helpers exposed as Platform.Function.*
• HTTP GET/POST calls
• JSON parsing, URL encoding
• AMPscript variable bridge

// No Platform.Load needed
var email = Platform.Function.Lookup("Subscribers", "Email", "SubscriberKey", sk);
var now   = Platform.Function.Now();

Show test script

<script runat="server">
/*
 * Chapter: Platform Functions
 * Proves:
 *   1. Platform.Function.Now without Core load.
 * EXPECTED OUTPUT: every line starts with PASS.
 */
function assert(id, actual, expected) {
    Platform.Response.Write((actual === expected ? "PASS " : "FAIL ") + id + " -> [" + actual + "]\n");
}
function typeOfThunk(fn) {
    try { return "" + fn(); } catch (ex) { return "THREW:" + ("" + ex.message); }
}
var now = Platform.Function.Now();
assert("Now typeof", typeof now === "string" || typeof now === "object" ? "ok" : typeof now, "ok");
</script>

Core Library

Requires Platform.Load("core", "1.1.5") to be called before any Core object is used.

Best for:

• Object-oriented CRUD when you prefer .Init() / .Rows.Add() patterns
• Accessing SFMC object schemas (DataExtension.Fields)
• Email and subscriber management operations
• Tracking event retrieval (automation context)

Platform.Load("core", "1.1.5");

var de = DataExtension.Init("MyDE");
var filter = { Property: "Status", SimpleOperator: "equals", Value: "active" };
var rows = de.Rows.Retrieve(filter); // works on CloudPages too — the filter is optional

for (var i = 0; i < rows.length; i++) {
    Write(rows[i]["Email"] + "<br>");
}

Platform.Load version matters. Always use "1.1.5". Older versions ("1", "1.1.1") have known bugs that are fixed in 1.1.5. Missing the version argument also causes issues.

Show test script

<script runat="server">
/*
 * Chapter: Core Library
 * Proves:
 *   1. After Load, DataExtension is available.
 * EXPECTED OUTPUT: every line starts with PASS.
 */
function assert(id, actual, expected) {
    Platform.Response.Write((actual === expected ? "PASS " : "FAIL ") + id + " -> [" + actual + "]\n");
}
function typeOfThunk(fn) {
    try { return "" + fn(); } catch (ex) { return "THREW:" + ("" + ex.message); }
}
Platform.Load("core", "1.1.5");
assert("DataExtension after Load", typeOfThunk(function () { return typeof DataExtension; }), "object");
</script>

WSProxy — A Third Option

For SOAP API operations, WSProxy (available without Platform.Load) is usually the best choice:

var proxy = new Script.Util.WSProxy();
var cols  = ["Name", "CustomerKey", "RowCount"];
var result = proxy.retrieve("DataExtension", cols);

WSProxy vs Core library:

Aspect	WSProxy	Core Library
Requires Platform.Load	No	Yes
Access to all SFMC objects	Yes	Limited set
Retrieve performance	Faster (batch)	Slower
API style	SOAP-over-JSON	Object-oriented
Multi-BU impersonation	Yes	No
Best for	SOAP-heavy work, batch ops	Simple CRUD patterns

Show test script

<script runat="server">
/*
 * Chapter: WSProxy
 * Proves:
 *   1. new Script.Util.WSProxy() constructs.
 * EXPECTED OUTPUT: every line starts with PASS.
 */
function assert(id, actual, expected) {
    Platform.Response.Write((actual === expected ? "PASS " : "FAIL ") + id + " -> [" + actual + "]\n");
}
function typeOfThunk(fn) {
    try { return "" + fn(); } catch (ex) { return "THREW:" + ("" + ex.message); }
}
var proxy = new Script.Util.WSProxy();
assert("WSProxy object", typeof proxy, "clr");
</script>

Choosing the Right Tool

Task	Recommended
Lookup single DE value	Platform.Function.Lookup()
Lookup multiple rows	Platform.Function.LookupRows()
Insert/update/delete DE rows	Platform.Function.InsertData/UpdateData/UpsertData/DeleteData
Complex DE retrieval with sorting	Platform.Function.LookupOrderedRows()
Read DE rows (any context)	DataExtension.Init().Rows.Retrieve()
Full SFMC object CRUD	new Script.Util.WSProxy()
Subscriber management	Subscriber.Init() or WSProxy
External HTTP	Script.Util.HttpRequest

→ Return to Getting Started or continue to Language Guide

Show test script

<script runat="server">
/*
 * Chapter: Choosing the Right Tool
 * Proves:
 *   1. Platform.Function.Lookup exists without Core; DataExtension needs Core.
 * EXPECTED OUTPUT: every line starts with PASS.
 */
function assert(id, actual, expected) {
    Platform.Response.Write((actual === expected ? "PASS " : "FAIL ") + id + " -> [" + actual + "]\n");
}
function typeOfThunk(fn) {
    try { return "" + fn(); } catch (ex) { return "THREW:" + ("" + ex.message); }
}
assert("Lookup typeof", typeof Platform.Function.Lookup, "clrmethodinfo");
assert("Platform.Function available without Core", typeof Platform.Function, "clr");
</script>