salsa-dude / js-looping-and-iteration-filter-lab-dc-web-100818

Filter Lab

Problem Statement

The filter method is one of the core iterator methods in JavaScript. It's a powerful tool for reducing a set of data into a set of data you want.

Objectives

1. Use filter to work with Strings as well as Objects
2. Write a function to case-insensitively match strings
3. Write a function to partially match substrings
4. Write a function to match object values to a provided string

Use filter to work with Strings as well as Objects

This lab contains an array of drivers with various information. We need to write methods using the filter method so that Scuber employees can easily query the data. Be sure to run the tests to get a feel for the types of problems this lab is asking you to solve before you start writing JavaScript code.

Write a Function To Case-insensitively Match strings

Write findMatching- This function takes an array of drivers and a string as arguments, and returns the matching list of drivers. The function should be case insensitive.

Write a Function To Partially Match Substrings

Write fuzzyMatch - This function takes an array of drivers and a string as arguments for querying the array, and returns all drivers whose names begin with the provided letters.

Write a Function To Match object Values To a Provided string

Write matchName - This function takes an array of drivers and a string as arguments. In this function, each element of the drivers array is a JavaScript object that has a property of name. The function should return each element whose name property matches the provided string argument.

Conclusion

While its simple truthy / falsey "testing" of each element in a collection is conceptually simple, the power of rejecting or selecting the things you want (or don't want) from a set is an awesome capability. Further, that filter returns an Array means that you can apply map or reduce immediately after e.g.

students.filter( s => !!s.permissionSlip && s.isVegetarian)
  .reduce( (orders, s) => orders.push(s.preferredMeal), [])`

// => "What are the preferred meals for vegetarian students who are allowed to
go on the field trip?"

means you can write terse code that loses little expressivity.

Resources

• MDN: Filter

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