I will put it together for myself.
** Controller model created **
routes.erb
  Rails.application.routes.draw do
    resources :posts do
      resources :comments, only: [:create, :destroy]
      resource :likes, only: [:create, :destroy]
    end
  end
likes becomes ** resource ** because it is not necessary to give an ID
post.rb
  def liked_by?(user)
    likes.where(user_id: user.id).exists?
  end
You can check if you like it
likes_controller.rb
class LikesController < ApplicationController
  def create
    @post = Post.find_by(id: params[:post_id])
    #Conditions to prevent continuous clicks
    unless @post.liked_by?(current_user)
      @like = current_user.likes.new(post_id: @post.id)
      @like.save
    end
  end
  def destroy
    @post = Post.find_by(id: params[:post_id])
    @like = current_user.likes.find_by(post_id: @post.id)
    @like.destroy
  end
end
Since redirects are not required for create and destroy respectively, delete them if they are listed.
ruby:posts/show.html.slim
#Give an id because it is necessary to make it Ajax
div id='like_#{ @post.id }'
   #Partial like icon
   = render 'like', post: @post
ruby:posts/_like.html.slim
#Like Delete
- if post.liked_by?(current_user)
  = link_to post_likes_path(post), method: :delete, remote: true do
    i.fas.fa-heart style='color: red;'
    = post.likes.count
#How nice
- else
  = link_to post_likes_path(post), method: :post, remote: true do
    i.far.fa-heart
    = post.likes.count
Call a JavaScript file by adding ** remote: true **
ruby:likes/create.js.erb
$("#like_<%= @post.id %>").html("<%= j(render 'posts/like', post: @post ) %>");
ruby:likes/destroy.js.erb
$("#like_<%= @post.id %>").html("<%= j(render 'posts/like', post: @post ) %>");
**Complete! ** **
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