simplify ajax.js implementation (#157)

* simplify ajax.js implementation

* fix typo

routes/_utils/ajax.js

@@ -7,6 +7,15 @@ function fetchWithTimeout (url, options) {
   })
 }
 
+function makeOpts (method, headers) {
+  return {
+    method,
+    headers: Object.assign(headers || {}, {
+      'Accept': 'application/json'
+    })
+  }
+}
+
 async function throwErrorIfInvalidResponse (response) {
   let json = await response.json()
   if (response.status >= 200 && response.status < 300) {
@@ -18,96 +27,66 @@ async function throwErrorIfInvalidResponse (response) {
   throw new Error('Request failed: ' + response.status)
 }
 
-async function _post (url, body, headers, timeout) {
+async function _fetch (url, options, timeout) {
   let fetchFunc = timeout ? fetchWithTimeout : fetch
-  let opts = {
+  let response = await fetchFunc(url, options)
-    method: 'POST'
-  }
-  if (body) {
-    let isFormData = body instanceof FormData
-    opts.headers = Object.assign(headers, isFormData ? {
-      'Accept': 'application/json'
-    } : {
-      'Accept': 'application/json',
-      'Content-Type': 'application/json'
-    })
-    opts.body = isFormData ? body : JSON.stringify(body)
-  } else {
-    opts.headers = Object.assign(headers, {
-      'Accept': 'application/json'
-    })
-  }
-  let response = await fetchFunc(url, opts)
   return throwErrorIfInvalidResponse(response)
 }
 
+async function _putOrPost (url, body, headers, timeout, method) {
+  let opts = makeOpts(method, headers)
+  if (body) {
+    if (body instanceof FormData) {
+      opts.body = body
+    } else {
+      opts.body = JSON.stringify(body)
+      opts.headers['Content-Type'] = 'application/json'
+    }
+  }
+  return _fetch(url, opts, timeout)
+}
+
+async function _post (url, body, headers, timeout) {
+  return _putOrPost(url, body, headers, timeout, 'POST')
+}
+
 async function _put (url, body, headers, timeout) {
-  let fetchFunc = timeout ? fetchWithTimeout : fetch
+  return _putOrPost(url, body, headers, timeout, 'PUT')
-  let opts = {
-    method: 'PUT'
-  }
-  if (body) {
-    opts.headers = Object.assign(headers, {
-      'Accept': 'application/json',
-      'Content-Type': 'application/json'
-    })
-    opts.body = JSON.stringify(body)
-  } else {
-    opts.headers = Object.assign(headers, {
-      'Accept': 'application/json'
-    })
-  }
-  let response = await fetchFunc(url, opts)
-  return throwErrorIfInvalidResponse(response)
 }
 
 async function _get (url, headers, timeout) {
-  let fetchFunc = timeout ? fetchWithTimeout : fetch
+  return _fetch(url, makeOpts('GET', headers), timeout)
-  let response = await fetchFunc(url, {
-    method: 'GET',
-    headers: Object.assign(headers, {
-      'Accept': 'application/json'
-    })
-  })
-  return throwErrorIfInvalidResponse(response)
 }
 
 async function _delete (url, headers, timeout) {
-  let fetchFunc = timeout ? fetchWithTimeout : fetch
+  return _fetch(url, makeOpts('DELETE', headers), timeout)
-  let response = await fetchFunc(url, {
-    method: 'DELETE',
-    headers: Object.assign(headers, {
-      'Accept': 'application/json'
-    })
-  })
-  return throwErrorIfInvalidResponse(response)
 }
 
-export async function put (url, body, headers = {}) {
+export async function put (url, body, headers) {
   return _put(url, body, headers, false)
 }
 
-export async function putWithTimeout (url, body, headers = {}) {
+export async function putWithTimeout (url, body, headers) {
   return _put(url, body, headers, true)
 }
 
-export async function post (url, body, headers = {}) {
+export async function post (url, body, headers) {
   return _post(url, body, headers, false)
 }
 
-export async function postWithTimeout (url, body, headers = {}) {
+export async function postWithTimeout (url, body, headers) {
   return _post(url, body, headers, true)
 }
 
-export async function getWithTimeout (url, headers = {}) {
+export async function getWithTimeout (url, headers) {
   return _get(url, headers, true)
 }
 
-export async function get (url, headers = {}) {
+export async function get (url, headers) {
   return _get(url, headers, false)
 }
 
-export async function deleteWithTimeout (url, headers = {}) {
+export async function deleteWithTimeout (url, headers) {
   return _delete(url, headers, true)
 }