Add linting with eslint in NeoVim, with a few bugs.

plugin/ale/cursor.vim

@@ -0,0 +1,72 @@
+if exists('g:loaded_ale_cursor')
+    finish
+endif
+
+let g:loaded_ale_cursor = 1
+
+" This function will perform a binary search to find a message from the
+" loclist to echo when the cursor moves.
+function! s:BinarySearch(loclist, line, column)
+    let min = 0
+    let max = len(a:loclist) - 1
+    let last_column_match = -1
+
+    while 1
+        if max < min
+            return last_column_match
+        endif
+
+        let mid = (min + max) / 2
+        let obj = a:loclist[mid]
+
+        " Binary search to get on the same line
+        if a:loclist[mid]['lnum'] < a:line
+            let min = mid + 1
+        elseif a:loclist[mid]['lnum'] > a:line
+            let max = mid - 1
+        else
+            let last_column_match = mid
+
+            " Binary search to get the same column, or near it
+            if a:loclist[mid]['col'] < a:column
+                let min = mid + 1
+            elseif a:loclist[mid]['col'] > a:column
+                let max = mid - 1
+            else
+                return mid
+            endif
+        endif
+    endwhile
+endfunction
+
+function! ale#cursor#TruncatedEcho(message)
+    let message = a:message
+    " Change tabs to spaces.
+    let message = substitute(message, "\t", ' ', 'g')
+    " Remove any newlines in the message.
+    let message = substitute(message, "\n", '', 'g')
+
+    let truncated_message = join(split(message, '\zs')[:&columns - 2], '')
+
+    " Echo the message truncated to fit without creating a prompt.
+    echo truncated_message
+endfunction
+
+function! ale#cursor#EchoCursorWarning()
+    let pos = getcurpos()
+
+    let index = s:BinarySearch(b:ale_loclist, pos[1], pos[2])
+
+    if index >= 0
+        call ale#cursor#TruncatedEcho(b:ale_loclist[index]['text'])
+    else
+        echo
+    endif
+endfunction
+
+if g:ale_echo_cursor
+    augroup ALECursorGroup
+        autocmd!
+        autocmd CursorMoved * call ale#cursor#EchoCursorWarning()
+    augroup END
+endif