docs: Move JSDoc type definitions to unified location

pr npm#15

* docs: Move JSDoc type definitions to unified location (tats-u#1)

This moves the JSDoc type definitions to the top of the file.

* docs: Fix typos

index.js

@@ -14,6 +14,24 @@ cmdShim.ifExists = cmdShimIfExists
 
 /**
  * @typedef {import('./index').Options} Options
+ *
+ * @typedef {object} RuntimeInfo Information of runtime and its arguments
+ * of the script `target`, defined in the shebang of it.
+ * @property {string|null} [program] If `program` is `null`, the program may
+ * be a binary executable and can be called from shells by just its path.
+ * (e.g. `.\foo.exe` in CMD or PowerShell)
+ * @property {string} additionalArgs Additional arguments embedded in the shebang and passed to `program`.
+ * `''` if nothing, unlike `program`.
+ *
+ * @callback ShimGenerator Callback functions to generate scripts for shims.
+ * @param {string} src Path to the executable or script.
+ * @param {string} to Path to the shim(s) that is going to be created.
+ * @param {Options} opts Options.
+ * @return {string} Generated script for shim.
+ *
+ * @typedef {object} ShimGenExtTuple
+ * @property {ShimGenerator} generator The shim generator function.
+ * @property {string} extension The file extension for the shim.
  */
 
 const fs = require('mz/fs')
@@ -125,7 +143,7 @@ function writeShimsPreCommon (target) {
  */
 function writeAllShims (src, to, srcRuntimeInfo, opts) {
   opts = Object.assign({}, DEFAULT_OPTIONS, opts)
-  /** @type {Array<[ShimGenerator, string]>} */
+  /** @type {ShimGenExtTuple[]} */
   const generatorAndExts = [{ generator: generateShShim, extension: '' }]
   if (opts.createCmdFile) {
     generatorAndExts.push({ generator: generateCmdShim, extension: '.cmd' })
@@ -158,17 +176,6 @@ function writeShimPost (target) {
   return chmodShim(target)
 }
 
-/**
- * Infomation of runtime and its arguments of the script `target`, defined in the shebang of it.
- *
- * @typedef {object} RuntimeInfo
- * @property {string|null} [program] If `program` is `null`, the program may
- * be a binary executable and can be called from shells by just its path.
- * (e.g. `.\foo.exe` in CMD or PowerShell)
- * @property {string} additionalArgs Additional arguments embedded in the shebang and passed to `program`.
- * `''` if nothing, unlike `program`.
- */
-
 /**
  * Look into runtime (e.g. `node` & `sh` & `pwsh`) and its arguments
  * of the target program (script or executable).
@@ -185,7 +192,7 @@ function searchScriptRuntime (target) {
       const shebang = firstLine.match(shebangExpr)
       if (!shebang) {
         // If not, infer script type from its extension.
-        // If the inferrence fails, it's something that'll be compiled, or some other
+        // If the inference fails, it's something that'll be compiled, or some other
         // sort of script, and just call it directly.
         const targetExtension = path.extname(target).toLowerCase()
         return Promise.resolve({
@@ -213,7 +220,7 @@ function searchScriptRuntime (target) {
  */
 function writeShim (src, to, srcRuntimeInfo, generateShimScript, opts) {
   const defaultArgs = opts.preserveSymlinks ? '--preserve-symlinks' : ''
-  // `Array.prototype.flter` removes ''.
+  // `Array.prototype.filter` removes ''.
   // ['--foo', '--bar'].join(' ') and [].join(' ') returns '--foo --bar' and '' respectively.
   const args = [srcRuntimeInfo.additionalArgs, defaultArgs].filter(arg => arg).join(' ')
   opts = Object.assign({}, opts, {
@@ -226,16 +233,6 @@ function writeShim (src, to, srcRuntimeInfo, generateShimScript, opts) {
     .then(() => writeShimPost(to))
 }
 
-/**
- * Callback functions to generate scripts for shims.
- * @callback ShimGenerator Callback functions to generate scripts for shims.
- *
- * @param {string} src Path to the executable or script.
- * @param {string} to Path to the shim(s) that is going to be created.
- * @param {Options} opts Options.
- * @return {string} Generated script for shim.
- */
-
 /**
  * Generate the content of a shim for CMD.
  *