Platform vs Core

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

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

The Two Layers

SSJS Runtime
├── Global functions     (Write, Stringify, ContentBlockByKey, …)
├── Platform             (always available, no Load required)
│   ├── Platform.Function.*    (~55 methods)
│   ├── Platform.Variable.*    (AMPscript bridge)
│   ├── Platform.Response.*    (HTTP response)
│   ├── Platform.Request.*     (HTTP request)
│   └── Platform.ClientBrowser.*
└── 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)

Platform.Function.*

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

Best for:

• Data Extension lookups and writes in CloudPages and emails
• String/date/math operations
• Crypto (Base64, SHA, AES encryption)
• 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();
var hash  = Platform.Function.SHA256(email);

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); // ⚠️ Does NOT work on CloudPages

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.

WSProxy — A Third Option

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

var proxy = new 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

Choosing the Right Tool

Task	Recommended
Lookup single DE value	Platform.Function.Lookup()
Lookup multiple rows (CloudPage)	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 (Automation only)	DataExtension.Init().Rows.Retrieve()
Full SFMC object CRUD	new WSProxy()
Subscriber management	Subscriber.Init() or WSProxy
External HTTP	Script.Util.HttpRequest

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