GraphQL complex cURL query (GitHub API v4)

The problem is that the query is JSON stringified, in your request you add new lines in the JSON string field query which is not permitted :

curl -H "Authorization: token YOUR_TOKEN" \
     -H  "Content-Type:application/json" \
     -d '{ 
          "query": "{ viewer { watching(first: 3, orderBy: {field: UPDATED_AT, direction: DESC}) { nodes { refs(refPrefix: \"refs/heads/\", orderBy: {direction: DESC, field: TAG_COMMIT_DATE}, last: 100) { nodes { target { ... on Commit { history(first: 10) { ...CommitFragment } }}}}}}} rateLimit { limit cost remaining resetAt}}fragment CommitFragment on CommitHistoryConnection { nodes { message author { name avatarUrl(size: 30) } } }"
      }' https://api.github.com/graphql

You can also use bash parameter expansion to remove new lines and escape double quotes :

token="YOUR_TOKEN"
query='{
  viewer {
    watching(first: 3, orderBy: {field: UPDATED_AT, direction: DESC}) {
      nodes {
        refs(refPrefix: "refs/heads/", orderBy: {direction: DESC, field: TAG_COMMIT_DATE}, last: 100) {
          nodes {
            target {
              ... on Commit {
                history(first: 10) {
                  ...CommitFragment
                }
              }
            }
          }
        }
      }
    }
  }
  rateLimit {
    limit
    cost
    remaining
    resetAt
  }
}

fragment CommitFragment on CommitHistoryConnection {
  nodes {
    message
    author {
      name
      avatarUrl(size: 30)
    }
  }
}'
queryStr="${query//[$'\n|\r\n']}"

curl -s -H "Authorization: token $token" \
     -H  "Content-Type:application/json" \
     -d '{ 
          "query": "'"${queryStr//[\"]/\\\"}"'"
      }' https://api.github.com/graphql

In case of Javascript, if you use XMLHttpRequest :

var http = new XMLHttpRequest();
var url = "https://api.github.com/graphql";
http.open("POST", url, true);

http.setRequestHeader("Content-type", "application/json");
http.setRequestHeader("Authorization", "token YOUR_TOKEN");

http.onreadystatechange = function() {
    if (http.readyState == 4 && http.status == 200) {
        alert(http.responseText);
    }
}

http.send(JSON.stringify({
    "query": '{ viewer { watching(first: 3, orderBy: {field: UPDATED_AT, direction: DESC}) { nodes { refs(refPrefix: "refs/heads/", orderBy: {direction: DESC, field: TAG_COMMIT_DATE}, last: 100) { nodes { target { ... on Commit { history(first: 10) { ...CommitFragment } }}}}}}} rateLimit { limit cost remaining resetAt}}fragment CommitFragment on CommitHistoryConnection { nodes { message author { name avatarUrl(size: 30) } } }'
}));

You can also find examples using apollo-client and graphql.js