Ruby on rails
By developing a wrapper Gem for webpack, Rails 6 attempted to address this issue. The gem known as Webpacker utilizes the well-known convention over the configuration of Rails to enable the usage of the most recent JS libraries while preserving certainly sensible defaults. The biggest problem with this was that if you wanted to move away from those norms, you needed a deeper understanding of Webpacker. Sadly, it failed to resolve the problems it was intended to, necessitating the need for a fresh strategy.
Importmap is a feature of Rails 7. There are a few reasons why this method of controlling JavaScript in your apps was chosen. First, all relevant browsers now implement ES6. Firefox, Chrome, Edge, and Safari. Second, since HTTP/2 is now the standard, a single connection can respond to a client with a number of tiny files. You can now uninstall your JavaScript bundle
How does the map method work
The map method in Ruby requires an enumerable object (the object you call it on) and a block in order to function.
The block is then executed for each element in the enumerable while being given the current element as an argument. The final step is to build the resulting array using the block's evaluation result.
example
[1, 2].map { |n| n + 2 } # => [3, 4]
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This example creates a new array by applying the block (i.e. |n| n + 2 ) to each element in the first array (i.e. [1, 2]) one at a time.
What does map(&:name) mean in Ruby?
When all you have to do inside the block is call a method, using this shorthand syntax is helpful.
[1, 2, 3].map { |n| n.odd? }
# could be written as
[1, 2, 3].map(&:odd?)
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Map And remove Nil Values
You might want to remove any nil values that are present in the resulting array. Here are some options for doing it.
[1, 2, 3].map { |n| n == 1? n : nil } # => [1, nil, nil]
[1, 2, 3].
select { |n| n == 1 ? n : nil } # => [1]
[1, 2, 3].
map { |n| n == 1 ? n : nil }.compact # => [1]
[1, 2, 3].map { |n| n == 1 ? n : nil } - [nil] # => [1]
[1, 2, 3].map { |n| n == 1 ? n : nil }.
reject(&:nil?) # => [1]
[1, 2, 3].
reduce([]) do |memo, n|
memo << n if n == 1
memo
End
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How to map with index
An index can be useful at times. You might want to add the index after the value. Or perhaps you have a stronger defence
["a", "b", "c"].each_with_index.map { |n, i| n + i+1.to_s } # => ["a1", "b2", "c3"]
["a", "b", "c"].map.with_index { |n, i| n + i+1.to_s } # => ["a1", "b2", "c3"]
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Ruby map examples
Doubling numbers
array = [5,7,9]
array.map { |n| n * 2 }
# [10, 14, 18]
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Convert strings to integers
array = ["111", "211", "51"]
array.map { |str| str.to_i }
# [111, 211, 51]
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Convert hash values to symbols
hash = { potato: "protein", banana: "fruit" }
hash.map { |k,v| [k, v.to_sym] }.to_h
# {:potato=>:protein, :banana=>:fruit}
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Map vs each
The outcome of applying the block on the array's elements is collected using map. Additionally, you can execute the block across the items without collecting values by using each. More information on employing each technique is available here.
Example
If the names array contains the following data
names = [ "Dan", "Stella", "Elly"]
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Then names.map will uppercase all the letter of each name
names.map { |name| name.upcase }
=> ["DAN", "STELLA", "ELLY"]
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But in the names.each it will uppercase only the first character of the names
names.each { |name| name.upcase }
=> ["Dan", "Stella", "Elly"]
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Map vs collect
There is no distinction because they are each other's aliases. However, map is a more well-known name for what it does than gather.
Example
If we look at the example we can find that both performs the same function like if
a = [1,2,3,4,5,6]
a.map! {|x| x + 1}
=> [2, 3, 4, 5, 6, 7]
a = a.collect {|x| x + 1}
puts a.inspect
=> [2, 3, 4, 5, 6, 7]
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Map vs select
The ruby maps technique is distinct from map vs. select. With select, all objects for which the block gives a truthy result are returned (i.e. not nil or false).
Example
a = [1,2,3,4,5]
a = a.select {|x| x > 2}
puts a.inspect
=> [3, 4, 5]
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Selects return a new array by applying the given conditions while if we look at the map it will simply return the array in its original form
a.map[a] will simply return the original array
Import Maps
Directly from the browser, you can import JavaScript modules by utilizing logical names that correspond to versioned/digested files. Therefore, utilizing JavaScript libraries designed for ES modules (ESM), you can create contemporary JavaScript applications without the requirement for transpiling or bundling. You won't require Webpack, Yarn, npm, or any other JavaScript toolchain components as a result. The asset pipeline that comes with Rails is all you need.
By using this method, many little JavaScript files rather than a single large JavaScript file will be shipped. Due to improved cache dynamics, HTTP/2 no longer entails a significant performance penalty during first transit and instead provides significant gains over the long term. Previously, every modification to any JavaScript file contained in your large bundle would invalidate the cache for the entire bundle; today, only that particular file's cache is affected.
How to import ruby on rails
Import maps are not a Rails-specific solution, that much is clear. They are an existing option that the Rails team believed would be the best method to introduce Javascript as a sensible default in Rails apps. The fundamental idea is that instead of needing to specify the precise location of where the library may be found, you can import Javascript libraries into your application just by referring to them by name. Import maps are essentially just "bare module specifiers" with strings substituted. You may recognize "bare module specifiers" by their appearance: import React from "react." To load Javascript code into the current file, just entering imports in this manner is not yet acceptable.
If you really want to, you can learn more about the ESM loader spec, which defines the currently acceptable methods of doing this, in the Node documentation.
When loading Javascript code, one of the following specifiers must be provided in order to be ESM compatible.
Importing React from "/Users/Odin/projects/TOP/node modules/react" requires an absolute path.
import relative path From "./node modules/react," run React.
import React from "https://ga.jspm.io/npm:react@17.0.1/index.js" in the URL scheme
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The "bare module specifiers" can be mapped to one of the three ways of loading ESM JavaScript packages using the importmap-rails gem.
Example
# config/importmap.rb pin "react", to: "https://ga.jspm.io/npm:react@17.0.2/ruby.js"
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As a result, whenever you see import React from "react" in the code, what you're really seeing is
import React from "https://ga.jspm.io/npm:react@17.0.2/ruby.js".
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Frequently Asked Questions
How is the maps in ruby on rails implemented?
The map method in Ruby requires an enumerable object (the object you call it on) and a block in order to function. The block is then executed for each element in the enumerable while being given the current element as an argument. The final step is to build the resulting array using the block's evaluation result.
What is lambda in Ruby?
A lambda is an object in Ruby that is comparable to a proc. A lambda, in contrast to a proc, accepts a predetermined amount of arguments and returns to the caller function rather than exiting on its own.
What is &Block in Ruby?
Ruby code can be sent into a method using the &block, which is then evaluated within the method's scope. According to the code in your example, a named partial cart will be displayed in a div.
Conclusion
In this article, we have discussed thoroughly the introduction to ruby on rails, maps in ruby on rails working with maps in ruby on rails, maps in ruby on rails syntax, a brief description of ruby on rails, how the map method works, map and remove nil values, how to map with index in detail.
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