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Lodash _.partial


The lodash _.partial method is used to create a new function by partially applying arguments to an existing function. This means that some of the parameters of the original function are fixed or pre-set, while others remain open for future input.

This method takes two or more arguments. The first argument is the function that you want to partially apply arguments to. The remaining arguments are the arguments you want to pre-set. The new function that is returned can then be called with the remaining arguments that were not initially set.

Here is an example using _.partial:

function greeting(greetingType, name) { 
  console.log(`${greetingType}, ${name}!`); 

const sayHello = _.partial(greeting, "Hello");
sayHello("John"); // will log "Hello, John!"

const sayGoodbye = _.partial(greeting, "Goodbye");
sayGoodbye("Kate"); // will log "Goodbye, Kate!"

In the example above, the greeting function takes two parameters: a greetingType and a name. Using _.partial, we are able to create two new functions that pre-set the greetingType parameter, while leaving the name parameter open for future input.

Using _.partial can be helpful with functions that have many parameters, as it allows you to reuse some of the parameters and only change the ones that need to be changed.

Overall, _.partial is a useful method for creating new functions by partially applying arguments to an existing function.