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Lodash _.assignWith


The lodash _.assignWith method is a powerful utility method that provides the ability to merge multiple source objects into a single destination object. It is a method that is commonly used in JavaScript programming to create new objects by combining properties from multiple source objects.

The _.assignWith method takes a destination object as the first parameter and one or more source objects as subsequent parameters. The method then iterates over the source objects and assigns the properties to the destination object. It also allows for custom logic to be used for merging the properties of the source objects.

One of the key features of the _.assignWith method is that it does not create a new object, but instead modifies the destination object. This can be extremely useful when working with mutable objects in JavaScript.

When using the _.assignWith method, a customizer function can be provided as a final parameter. The customizer function is called for each property that is about to be merged into the destination object. The customizer function takes three arguments: the value of the destination property, the value of the source property, and the key of the source property.

The customizer function is then responsible for returning the value that should be merged into the destination object. If the customizer function returns undefined, the default merging behavior is used.

In addition to the _.assignWith method, lodash provides a number of related functions for merging objects, such as _.merge and _.defaults. These functions provide different behavior when merging objects and can be useful in certain scenarios.

Overall, the lodash _.assignWith method is a powerful utility method for merging objects in JavaScript. Its flexibility and customizability make it a valuable tool for working with mutable objects and creating new objects from multiple sources.