local html = [[

<meta property="og:title" content="Example 1 A">

<meta property=og:title content="Example 2 B">

<meta property="og:title" content="Example 3 C" >

<meta property="og:title" content="Example 4 D" />

<meta property="og:title" content="Example 5 E"/>

<meta property=og:title content=Example 6 F/>

<meta property="og:title" content= "Example 7 G" />

<meta property="og:title" itemprop="image primaryImageOfPage" content="Example 8 H" />

<meta property='og:title' content='Example 9 I' />

<meta content="Example 10 J" property="og:title" >

<meta content="Example 11 K" property="og:title">

<meta content="Example 12 L" property="og:title"/>

<meta content="Example 13 M" property="og:title" />

<meta content="Example 14 N" property=og:title >

<meta content=Example 15 O property=og:title >

<meta content= "Example 16 P" property="og:title" />

<meta content="Example 17 Q" itemprop="image primaryImageOfPage"  property="og:title" />

<meta content= 'Example 18 R' property='og:title' />

]]

local meta_pattern = [[<meta (.-)/?>]]

for match in html:gmatch(meta_pattern) do

    local property = match:match([[property=%s*["']?(og:.-)["']?%s]])

    if not property then

        property = match:match([[property=["']?(og:.-)["']$]])

    end

    local content = match:match([[content=%s*["'](.-)["']%s]])

    if not content then

        content = match:match([[content=["']?(.-)["']$]])

    end

    if not content then

        content = match:match([[content=(.-) property]])

    end

    if not content then

        content = match:match([[content=(.-)$]])

    end

    print(property, '\t', content, '\t', match .. "|")

end