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Lodash _.has


The lodash _.has method is a utility function that checks if an object has a given property. It returns a boolean value indicating whether the object has the property or not. The method takes two arguments: the object to check and the property path to query.

The property path may be specified as either a string or an array of strings, with each element representing a key in the object. The _.has method traverses the object hierarchy to locate the property specified in the property path, and returns true if the property is found, false otherwise.

The _.has method can be used in a wide range of scenarios in JavaScript programming. For example, it can be used to test if an object has a certain property before attempting to read or write its value. This can help prevent errors and improve the robustness of the code.

In addition to its primary function of checking for property existence, the _.has method can also be used in functional programming techniques to compose more complex functions. For instance, it can be combined with other lodash methods like and _.filter to create advanced data transformations and filters.

Some examples of using the _.has method are:

const obj = { a: { b: 2 } };

_.has(obj, 'a'); // true
_.has(obj, 'a.b'); // true
_.has(obj, ['a', 'b']); // true

const arr = [{ a: 1 }, { b: 2 }];

_.filter(arr, _.partial(_.has, _, 'a')); //[{ a: 1 }], _.partial(_.get, _, 'b', 'unknown')); //[undefined, 2]

In summary, the _.has method is a powerful utility function for checking object property existence and can be used in various scenarios in JavaScript development.