datajs.js is a JavaScript library for data processing. It is mainly used to send requests to OData (Open Data Protocol) services, get data, and convert these data into JavaScript objects. OData is an open, REST-based, resource-oriented protocol for creating and consuming APIs for querying and manipulating data.
SAP UI5 is SAP's client UI technology for creating and running enterprise-class web applications. It can get data from various data sources including OData services, that's why you see datajs.js file when loading SAP UI5 application.
datajs.js provides a convenient way to handle OData services. For example, you can use it to send a GET request to an OData service to get data, a POST request to create a new data item, or a PUT or DELETE request to update or delete an existing data item.
Here's an example of using datajs.js to get data from an OData service:
OData.read(
"http://services.odata.org/V3/Northwind/Northwind.svc/Products",
function (data) {
for (var i = 0; i < data.results.length; i++) {
console.log(data.results[i].ProductName);
}
},
function (err) {
console.log(err.message);
}
);
In this example, OData.readthe method is used to send a GET request to the specified OData service URL. This URL usually returns a list of products. The second parameter of this method is a callback function, which will be called when the request is successful, and the returned data will be used as a parameter. In this callback function, we iterate through the returned data and print the name of each product to the console. The third parameter is another callback function that will be called when the request fails, with the error object as a parameter.
datajs.js can be used not only to get data, but also to create, update and delete data. For example, you can use OData.requestthe method to send POST, PUT, or DELETE requests. Here is an example of creating new data using datajs.js:
var product = {
ProductName: "New Product",
UnitPrice: 20
};
OData.request(
{
requestUri: "http://services.odata.org/V3/Northwind/Northwind.svc/Products",
method: "POST",
data: product
},
function (data) {
console.log("Product created with ID " + data.ProductID);
},
function (err) {
console.log(err.message);
}
);
In this example, we first define an object representing a new product. Then, we use OData.requestthe method to send a POST request to the specified OData service URL to create a new product. The first parameter of this method is an object that contains various parameters of the request, including the requested URL, method, and data. The second and third parameters of this method are callback functions, which are called when the request succeeds and fails, respectively.