Refactor running of local Node programs with a helper function

ale_linters/javascript/flow.vim

@@ -1,22 +1,13 @@
 " Author: Zach Perrault -- @zperrault
 " Description: FlowType checking for JavaScript files
 
-let g:ale_javascript_flow_executable =
-\   get(g:, 'ale_javascript_flow_executable', 'flow')
-
-let g:ale_javascript_flow_use_global =
-\   get(g:, 'ale_javascript_flow_use_global', 0)
+call ale#Set('javascript_flow_executable', 'flow')
+call ale#Set('javascript_flow_use_global', 0)
 
 function! ale_linters#javascript#flow#GetExecutable(buffer) abort
-    if ale#Var(a:buffer, 'javascript_flow_use_global')
-        return ale#Var(a:buffer, 'javascript_flow_executable')
-    endif
-
-    return ale#path#ResolveLocalPath(
-    \   a:buffer,
+    return ale#node#FindExecutable(a:buffer, 'javascript_flow', [
     \   'node_modules/.bin/flow',
-    \   ale#Var(a:buffer, 'javascript_flow_executable')
-    \)
+    \])
 endfunction
 
 function! ale_linters#javascript#flow#GetCommand(buffer) abort

ale_linters/javascript/jshint.vim

@@ -1,22 +1,13 @@
 " Author: Chris Kyrouac - https://github.com/fijshion
 " Description: JSHint for Javascript files
 
-let g:ale_javascript_jshint_executable =
-\   get(g:, 'ale_javascript_jshint_executable', 'jshint')
-
-let g:ale_javascript_jshint_use_global =
-\   get(g:, 'ale_javascript_jshint_use_global', 0)
+call ale#Set('javascript_jshint_executable', 'jshint')
+call ale#Set('javascript_jshint_use_global', 0)
 
 function! ale_linters#javascript#jshint#GetExecutable(buffer) abort
-    if ale#Var(a:buffer, 'javascript_jshint_use_global')
-        return ale#Var(a:buffer, 'javascript_jshint_executable')
-    endif
-
-    return ale#path#ResolveLocalPath(
-    \   a:buffer,
+    return ale#node#FindExecutable(a:buffer, 'javascript_jshint', [
     \   'node_modules/.bin/jshint',
-    \   ale#Var(a:buffer, 'javascript_jshint_executable')
-    \)
+    \])
 endfunction
 
 function! ale_linters#javascript#jshint#GetCommand(buffer) abort

ale_linters/javascript/standard.vim

@@ -1,25 +1,14 @@
 " Author: Ahmed El Gabri <@ahmedelgabri>
 " Description: standardjs for JavaScript files
 
-let g:ale_javascript_standard_executable =
-\   get(g:, 'ale_javascript_standard_executable', 'standard')
-
-let g:ale_javascript_standard_options =
-\   get(g:, 'ale_javascript_standard_options', '')
-
-let g:ale_javascript_standard_use_global =
-\   get(g:, 'ale_javascript_standard_use_global', 0)
+call ale#Set('javascript_standard_executable', 'standard')
+call ale#Set('javascript_standard_use_global', 0)
+call ale#Set('javascript_standard_options', '')
 
 function! ale_linters#javascript#standard#GetExecutable(buffer) abort
-    if ale#Var(a:buffer, 'javascript_standard_use_global')
-        return ale#Var(a:buffer, 'javascript_standard_executable')
-    endif
-
-    return ale#path#ResolveLocalPath(
-    \   a:buffer,
+    return ale#node#FindExecutable(a:buffer, 'javascript_standard', [
     \   'node_modules/.bin/standard',
-    \   ale#Var(a:buffer, 'javascript_standard_executable')
-    \)
+    \])
 endfunction
 
 function! ale_linters#javascript#standard#GetCommand(buffer) abort

ale_linters/javascript/xo.vim

@@ -1,25 +1,14 @@
 " Author: Daniel Lupu <lupu.daniel.f@gmail.com>
 " Description: xo for JavaScript files
 
-let g:ale_javascript_xo_executable =
-\   get(g:, 'ale_javascript_xo_executable', 'xo')
-
-let g:ale_javascript_xo_options =
-\   get(g:, 'ale_javascript_xo_options', '')
-
-let g:ale_javascript_xo_use_global =
-\   get(g:, 'ale_javascript_xo_use_global', 0)
+call ale#Set('javascript_xo_executable', 'xo')
+call ale#Set('javascript_xo_use_global', 0)
+call ale#Set('javascript_xo_options', '')
 
 function! ale_linters#javascript#xo#GetExecutable(buffer) abort
-    if ale#Var(a:buffer, 'javascript_xo_use_global')
-        return ale#Var(a:buffer, 'javascript_xo_executable')
-    endif
-
-    return ale#path#ResolveLocalPath(
-    \   a:buffer,
+    return ale#node#FindExecutable(a:buffer, 'javascript_xo', [
     \   'node_modules/.bin/xo',
-    \   ale#Var(a:buffer, 'javascript_xo_executable')
-    \)
+    \])
 endfunction
 
 function! ale_linters#javascript#xo#GetCommand(buffer) abort