DOMParser解析xml字符串

如题，实现如下：

var parser = new DOMParser()
var result = parser.parseFromString('<?xml version="1.0" encoding="UTF-8"?>' +

  '<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">' +
  '<plist version="1.0">' +
  '    <dict>' +
  '        <key>frames</key>' +
  '        <dict>' +
  '            <key>area_partner_1.png</key>' +
  '            <dict>' +
  '                <key>aliases</key>' +
  '                <array/>' +
  '                <key>anchor</key>' +
  '                <string>{0.5,0.5}</string>' +
  '                <key>spriteOffset</key>' +
  '                <string>{0,0}</string>' +
  '                <key>spriteSize</key>' +
  '                <string>{678,641}</string>' +
  '                <key>spriteSourceSize</key>' +
  '                <string>{678,641}</string>' +
  '                <key>textureRect</key>' +
  '                <string>{{1,1},{678,641}}</string>' +
  '                <key>textureRotated</key>' +
  '                <false/>' +
  '            </dict>' +
  '        </dict>' +
  '        <key>metadata</key>' +
  '        <dict>' +
  '            <key>format</key>' +
  '            <integer>3</integer>' +
  '            <key>pixelFormat</key>' +
  '            <string>RGBA8888</string>' +
  '            <key>premultiplyAlpha</key>' +
  '            <false/>' +
  '            <key>realTextureFileName</key>' +
  '            <string>wqer.png</string>' +
  '            <key>size</key>' +
  '            <string>{846,643}</string>' +
  '            <key>smartupdate</key>' +
  '            <string>$TexturePacker:SmartUpdate:0d31322d15aeee6aaabcfc82cc4676df:91776dda71b0a5779c04559a94ab5066:01c2a16656db932f59fe35247e90d956$</string>' +
  '            <key>textureFileName</key>' +
  '            <string>wqer.png</string>' +
  '        </dict>' +
  '    </dict>' +
  '</plist>', 'application/xml')

console.log(result)
const keys = result.getElementsByTagName('key')
const strings = result.getElementsByTagName('string')

const arr = []
for (var i = 0; i < keys.length; i++) {

  if (/.*\.png/.test(keys[i].innerHTML)) {
      arr.push(keys[i])
  }

}
console.log(arr)

var arr1 = []
arr.forEach(item => {

  arr1.push(item.nextElementSibling.getElementsByTagName('key'))

})
console.log(arr1)