Programming is an excellent exercise for your brain as programmers deal with never-ending situations like bugs, compiler, issues, deadlines, languages, etc. During all these times, other than the phenomenal codes, we produce MEMEs and a hell lot of MEMEs
\nMEMEs can light the environment for every programmer in the world. On that note, there is a famous saying-
\n“If debugging is the process of removing software bugs, then programming must be the process of putting them in – Edsger Dijkstra”
\nIf you have better ones, reply in the comments below and we’ll include them. Deno is a JavaScript/TypeScript runtime with secure defaults and great developer experience. It's built on V8, Rust, and Tokio.\nI suggest you watch these talks by Ryan: He talks about his mistakes with Nodejs here and a more in-depth look into deno here In this article, we're going to build a simple cli tool to demonstrate some of the features of deno. Our cli will be interacting with a COVID API to fetch live data. Requirement: make sure you have deno installed. If you don't, refer to this link. It's pretty straightforward. Deno has the entry file Here the After running the above code you will see the output as The first property in the object is always an array containing all arguments that did not have an option associated with them(i.e it doesn't match -f or --flag). If you do not pass a corresponding value to a flag, it defaults to true. I will be using the this postman doc for all the COVID related API and we will perform the below to action through our CLI. Let's write out the function for our first command, so our Here, we have an async function that returns the data from our API call. We're making a fetch request (yes, deno has browser functionality in-built) to the API endpoint to get the global stat of covid19. The function for the second command looks very similar, just we need to filter our data only for a particular country which is provided. We will now write our And our To test our program, we're going to run $ deno run You can build a lot with it, ranging from cli Programs to HTTP servers. Do have a look at one of my blog where I have built a basic calculator app using the abc module.What is Deno?
\nFeatures
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\nLet's Build Something!!!
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\nmod.ts so we will follow the same in this article if you are following this article along with the coding you can create a folder named covid-cli, inside that folder you can create a file called mod.ts and copy the below code there.
\nconst { args } = Deno;\nimport { parse } from "https://deno.land/std/flags/mod.ts";\n\nconsole.dir(parse(args));parse(args, options = {}); contains two parameters where args is an Array and options is an object, let try to run the above code using this cmd.
\ndeno run mod.ts arg1 -f hello --flag World --booleanFlag
\n{ _: [ "arg1" ], f: "hello", flag: "World", booleanFlag: true }\n
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\nmod.ts file will look like this.
\nconst { args } = Deno;\nimport { parse } from "https://deno.land/std/flags/mod.ts";\n\n// flags:\n// -h, --help: display help message\n// -g, --global: display global stats\n// -c, --country: get data of mentioned country\n\nconst BASE_URL: string = "https://api.covid19api.com/"\nconst parsedArgs = parse(args)\n\nasync function getGlobalStats() {\n const res = await fetch(`${BASE_URL}summary`)\n const data = await res.json();\n console.log(data["Global"])\n}
\nasync function getCountryStats(country: string) {\n if (country) {\n const res = await fetch(`${BASE_URL}summary`);\n const data = await res.json();\n const index = data["Countries"].findIndex((c: any) => c.Country.toLowerCase() === country.toLowerCase())\n if (index !== -1) {\n console.log(data["Countries"][index])\n } else {\n console.log("Country Not Found")\n }\n } else {\n console.log("Country Name is needed")\n }\n}main() function. We have a switch statement to check the first flag that was passed and calls the appropriate function. The default case simply displays a welcome message. Let add the below code in our mod.ts file
\nasync function main() {\n switch (Object.keys(parsedArgs)[1]) {\n case "help":\n case "h":\n console.log(displayHelpMsg());\n break;\n case "global":\n case "g":\n await getGlobalStats();\n break;\n case "country":\n case "c":\n let country = parsedArgs.c || parsedArgs.country || ""\n await getCountryStats(country)\n break;\n default:\n console.log(displayHelpMsg());\n }\n}\n\nmain()displayHelpMsg() will look something like this
\nfunction displayHelpMsg() {\n return "flags:\\n-h, --help: display help message\\n-g, --global: display global stats\\n-c, --country: get data of mentioned country ";\n}Testing Time!!!
\n--allow-net mod.ts -g. We should get the following result:\n
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