jq returns null or error when parsing json response [duplicate]

When parsing a json response using jq run from cmd.exe on a Windows 10 machine, I always get either a null response or an error when trying to get a value present in the JSON.

Here is the curl:

curl -X POST -H "Content-Type: application/json" -H "Accept: application/json" -H "Accept-Encoding: gzip, deflate" --compressed -d "{\"upc\": \"4002293401102\"}" "https://api.upcitemdb.com/prod/trial/lookup" | jq ".ean"

Here is the JSON response. For brevity, I shortened the full response as it's quite long.

{"code": "OK","total": 1,"offset": 0,"items": [    {"ean": "4002293401102","title": "Wusthof Gourmet 3-Inch Serrated Paring Knife","asin": "B0000DJYE3","elid": "192088094351"    }  ]}

Here is what I've tried in jq to obtain the EAN value. In parenthesis I put abbreviated errors I receive.

• jq ".items.ean" (I get: jq: error (at :0): Cannot index array with string "ean")
• jq "[items].ean" (I get: curl: Failed writing body)
• jq ".[items].ean" (I get: curl: Failed writing body)
• jq "[].items.ean" (I get: jq: error (at :0): Cannot index array with string "items")
• jq "[].[items].ean" (I get: curl: Failed writing body)
• jq ".items.[ean]" (I get: curl: Failed writing body"

I'm sure I'm using the wrong syntax for jq. Any ideas what I'm doing wrong? I just cannot seem to get the syntax of getting that value.