diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -37,8 +37,9 @@ This will scaffold a basic template for you 😎
 - [Learn how to use](https://docs.near.org/sdk/js/introduction) the library in your project
 - Check our [detailed examples and tutorials](https://docs.near.org/tutorials/welcome)
 - Find [source code examples](./examples) with common use cases
-- Lookup available features in [API reference](https://docs.near.org/sdk/near-sdk-js/reference)
+- Lookup available features in [API reference](https://near.github.io/near-sdk-js/)
 - 🏠 Learn more about NEAR on our [Documentation website](https://docs.near.org/)
+- Breaking features diff from [SDK 2.0.0 to 1.0.0](near-sdk-js@2.0.0-diff-1.0.0.md)
 
 ## Contributing
 
diff --git a/near-sdk-js@2.0.0-diff-1.0.0.md b/near-sdk-js@2.0.0-diff-1.0.0.md
new file mode 100644
index 00000000..04767ff4
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+++ b/near-sdk-js@2.0.0-diff-1.0.0.md
@@ -0,0 +1,195 @@
+# Breaking features diff from SDK 2.0.0 to 1.0.0
+## borsh data de/serializer for contract state
+* using for: new contracts or migrate from a borsh serialized contract
+[example](https://github.com/near/near-sdk-js/blob/develop/examples/src/status-message-borsh.js)
+```js
+@NearBindgen({
+    serializer(statusMessage) {
+        return borsh.serialize(schema, statusMessage);
+    },
+    deserializer(value) {
+        return borsh.deserialize(schema, value);
+    }
+})
+export class StatusMessage {
+    constructor() {
+        this.records = new Map()
+    }
+
+    @call({})
+    set_status({ message }) {
+        let account_id = near.signerAccountId()
+        env.log(`${account_id} set_status with message ${message}`)
+        this.records.set(account_id, message)
+    }
+
+    @view({})
+    get_status({ account_id }) {
+        env.log(`get_status for account_id ${account_id}`)
+        return this.records.get(account_id) || null
+    }
+}
+```
+
+## js contract migration with data fields
+### example1
+* using for: contract state migrations
+* [example](https://github.com/near/near-sdk-js/blob/develop/examples/src/status-message-migrate-add-field.js)
+```js
+import {NearBindgen, call, view, near, migrate, Vector, assert} from "near-sdk-js";
+
+class OldStatusMessage {
+  constructor() {
+    this.records = {};
+  }
+}
+
+@NearBindgen({})
+export class StatusMessage {
+  constructor() {
+    this.records = {};
+    this.new_fields = {}; // new added filed
+  }
+  ...
+
+  // Migrate from OldStatusMessage to StatusMessage
+  @migrate({})
+  migrateState() {
+    assert(this.records !== undefined, "Contract state should not be deserialized in @migrate");
+    // retrieve the current state from the contract
+    let records = JSON.parse(near.storageRead("STATE")).records;
+
+    this.records = records;
+    this.new_fields = {};
+  }
+}
+```
+### example2
+* another migration example can be found in [test-basic-updates.ava.js](./examples/__tests__/test-basic-updates.ava.js) with [old state contract](./examples/src/basic-updates-base.js) and new [new state contract](./examples/src/basic-updates-update.js).  
+with the test command in [examples directory](./examples):
+```shell
+pnpm run test:basic-updates
+```
+
+## auto reconstruct class from object by static json schema
+* use for contract serialzed by default method(json), the detail document is here: https://github.com/near/near-sdk-js/blob/develop/AUTO_RECONSCTRUCT_BY_JSON_SCHEME.md#the-schema-format
+* [example](https://github.com/near/near-sdk-js/blob/develop/examples/src/status-deserialize-class.js#L49)
+```js
+class Car {
+    static schema = {
+        name: "string",
+        speed: "number",
+    };
+    constructor() {
+        this.name = "";
+        this.speed = 0;
+    }
+
+    info() {
+        return this.name + " run with speed " + this.speed.toString()
+    }
+}
+
+class Truck {
+    static schema = {
+        name: "string",
+        speed: "number",
+        loads: UnorderedMap
+    };
+    constructor() {
+        this.name = "";
+        this.speed = 0;
+        this.loads = new UnorderedMap("tra");
+    }
+
+    info() {
+        return this.name + " run with speed " + this.speed.toString() + " with loads length: " + this.loads.toArray().length;
+    }
+}
+
+// sdk should first try if UnorderedMap has a static schema and use it to recursively decode.
+@NearBindgen({})
+export class StatusDeserializeClass {
+    static schema = {
+        truck: Truck,
+        efficient_recordes: UnorderedMap,
+        nested_efficient_recordes: {class: UnorderedMap, value: UnorderedMap},
+        nested_lookup_recordes:  {class: UnorderedMap, value: LookupMap},
+        vector_nested_group: {class: Vector, value: LookupMap},
+        lookup_nest_vec: { class: LookupMap, value: Vector },
+        unordered_set: UnorderedSet,
+        user_car_map: {class: UnorderedMap, value: Car },
+        big_num: 'bigint',
+        date: 'date'
+    };
+    constructor() {
+        this.is_inited = false;
+        this.records = {};
+        this.truck = new Truck();
+        this.messages = [];
+        this.efficient_recordes = new UnorderedMap("a");
+        this.nested_efficient_recordes = new UnorderedMap("b");
+        this.nested_lookup_recordes = new UnorderedMap("c");
+        this.vector_nested_group = new Vector("d");
+        this.lookup_nest_vec = new LookupMap("e");
+        this.unordered_set = new UnorderedSet("f");
+        this.user_car_map = new UnorderedMap("g");
+        this.big_num = 1n;
+        this.date = new Date();
+        this.message_without_schema_defined = "";
+        this.number_without_schema_defined = 0;
+        this.records_without_schema_defined = {};
+    }
+    ...
+}
+```
+
+## query data Nesting of objects in SDK Collections without Nested Collection's reconstructor
+* using for SDK Collections which has description in static json schema
+In [near-sdk-js 1.0.0](https://www.npmjs.com/package/near-sdk-js/v/1.0.0), users needed to call a `reconstructor` method in order for **Nested Collections** to be properly decoded:
+```typescript
+@NearBindgen({})
+export class Contract {
+    outerMap: UnorderedMap<UnorderedMap<string>>;
+
+    constructor() {
+        this.outerMap = new UnorderedMap("o");
+    }
+
+    @view({})
+    get({id, accountId}: { id: string; accountId: string }) {
+        const innerMap = this.outerMap.get(id, {
+            reconstructor: UnorderedMap.reconstruct,  // we need to announce reconstructor explicit
+        });
+        if (innerMap === null) {
+            return null;
+        }
+        return innerMap.get(accountId);
+    }
+}
+```
+In [near-sdk-js 2.0.0](https://www.npmjs.com/package/near-sdk-js/v/2.0.0) With schemas, this is no longer needed, as the SDK can correctly infer how to decode the Nested Collections:
+
+```typescript
+@NearBindgen({})
+export class Contract {
+    static schema = {
+      outerMap: {class: UnorderedMap, value: UnorderedMap}
+    };
+    
+    outerMap: UnorderedMap<UnorderedMap<string>>;
+
+    constructor() {
+        this.outerMap = new UnorderedMap("o");
+    }
+
+    @view({})
+    get({id, accountId}: { id: string; accountId: string }) {
+        const innerMap = this.outerMap.get(id);  // reconstructor can be infered from static schema
+        if (innerMap === null) {
+            return null;
+        }
+        return innerMap.get(accountId);
+    }
+}
+```