Add javascript example to get the WASM content (#473)

* Add javascript example to get the WASM content

* Update to preview 10

api/methods/getLedgerEntries.mdx

@@ -207,6 +207,8 @@ When you deploy a contract, first the code is "installed" (i.e. it is uploaded o
 
 #### Request the `LedgerKey` for the Contract Code
 
+##### Python
+
 ```python
 from stellar_sdk import xdr
 
@@ -230,6 +232,31 @@ print(
 # OUTPUT: AAAABq+aJSfjs7VXHWOwJGujK30xpTI3Zt98YN/As+O6b98jAAAAFA==
 ```
 
+##### JavaScript
+
+```javascript
+const { xdr } = require("soroban-client")
+function getLedgerKeyContractCode(contractId) {
+  let ledgerKey = xdr.LedgerKey.contractData(
+    new xdr.LedgerKeyContractData({
+      contract: xdr.ScAddress.scAddressTypeContract(contractId),
+      key: new xdr.ScVal.scvLedgerKeyContractInstance(),
+      durability: xdr.ContractDataDurability.persistent(),
+      bodyType: xdr.ContractEntryBodyType.dataEntry(),
+    })
+  );
+
+  return ledgerKey.toXDR('base64');
+}
+
+console.log(
+  getLedgerKeyContractCode(
+    "af9a2527e3b3b5571d63b0246ba32b7d31a5323766df7c60dfc0b3e3ba6fdf23"
+  )
+)
+// OUTPUT: AAAABq+aJSfjs7VXHWOwJGujK30xpTI3Zt98YN/As+O6b98jAAAAFA==
+```
+
 We then take our output from this function, and use it as the element in the `keys` array parameter in our call to the `getLedgerEntries` method.
 
 ```json
@@ -268,6 +295,8 @@ And the response we get contains the `LedgerEntryData` that can be used to find
 
 Now take the `xdr` field from the previous response's `result` object, and create a `LedgerKey` from the hash contained inside.
 
+##### Python
+
 ```python
 from stellar_sdk import xdr
 
@@ -293,8 +322,50 @@ print(
 # OUTPUT: AAAAB2QWKBCU9yGjzDJNxaEZpxEB6A8XsD2S/lKK/sViOLiC
 ```
 
+##### JavaScript
+
+```javascript
+const { xdr } = require("soroban-client")
+
+function getLedgerKeyWasmId(contractCodeLedgerEntryData) {
+
+  let entry = xdr.LedgerEntryData.fromXDR(
+    contractCodeLedgerEntryData,
+    "base64"
+  );
+
+  let instance = new xdr.ScContractInstance({
+    executable: entry.contractData()
+      .body()
+      .value()
+      .val()
+  });
+
+  let ledgerKey = xdr.LedgerKey.contractCode(
+    new xdr.LedgerKeyContractCode({
+      hash: xdr.ContractExecutable.contractExecutableWasm(instance.executable())
+        .wasmHash()
+        .instance()
+        .executable()
+        .wasmHash(),
+      bodyType: xdr.ContractEntryBodyType.dataEntry()
+    })
+  );
+
+  return ledgerKey.toXDR('base64');
+}
+
+console.log(
+  getLedgerKeyWasmId(
+    "AAAABq+aJSfjs7VXHWOwJGujK30xpTI3Zt98YN/As+O6b98jAAAAFAAAABIAAAAAZBYoEJT3IaPMMk3FoRmnEQHoDxewPZL+Uor+xWI4uII="
+  )
+)
+// OUTPUT: AAAAB2QWKBCU9yGjzDJNxaEZpxEB6A8XsD2S/lKK/sViOLiC
+```
+
 Now, finally we have a `LedgerKey` that correspond to the Wasm byte-code that has been deployed under the `ContractId` we started out with so very long ago. This `LedgerKey` can be used in a final request to the Soroban-RPC endpoint.
 
+
 ```json
 {
   "jsonrpc": "2.0",