Nano "Typescript" without compilation

Published at

3/28/2024

Categories

3 categories in total

Thanks to this post from Toby Farley (Shadow Chicken), I had an inspiration to build my own tiny little nano "typescript" running without compilation.

Ok, typescript provides much more, but if you only need some typechecks, this little routine would do the trick:

/* ==================================================
    Nano typeCheck
    Valid types
    "var": Variant - all types allowed 
    "string"
    "number"
    "bigInt"
    "boolean"
    "object"
    "array"
    "date"
    "set"
    "function"
  ================================================== */
  function typeCheck(v) {
  if ((typeof v) !== "object") throw (`Parameter must be Object in function ${typeCheck.caller.name}`)

  // Build return value array
  let res = Object.entries(v).map((a, i) => {
    let [typ, val] = a;  // get key/values
    typ = typ.charAt(0).toUpperCase() + typ.slice(1) // Capitalize
    if (typ === "Var")  // Variant type
      return val
    if (val.constructor.name !== typ) // check type
      throw (`Type error parameter ${i + 1} is not ${typ} in function ${typeCheck.caller.name}`)
    return (val)
  })
  return res
}

function myFunc(a,b,c,d) {
  typeCheck({ string: a, boolean: b, array: c, var: d })
  console.log(a)
  console.log(b)
  console.log(c)
  console.log(d)
}

myFunc( "5",  true, [1, 2, 3, 4, 5], "Do what you want")

You can also submit typ declaration with the parameters like this:

function myFunc(pars) {
  let [a, b, c, d] = typeCheck(pars)
  console.log(a)
  console.log(b)
  console.log(c)
  console.log(d)
}

myFunc({ string: "5", boolean: true, array: [1, 2, 3, 4, 5], var: "Do what you want" })

Types can be named using the standard type names with lower or upper case, so both would be accepted:

{ string: a, boolean: b, array: c, var: d }
{ String: a, Boolean: b, Array: c, Var: d }

Tell me, what you think.

P.S.: This post was changed after the first sumbission to show different ways of usage.

dev-resources.site

Nano "Typescript" without compilation