How to detect whethere if a JSON node exists

[Adnan]

In the following code, I want to process an json array (returned 
by the value of "posts") that might or might not have "com" key. 
If a "com" key does not exist, I want to ignore that item in the 
json array.

         uint[string] wordTable;

	const auto j = parseJSON(get(link));
	foreach (node; j["posts"].array()) {
		import std.stdio : writeln;
		import std.utf : decode;

		import std.algorithm: splitter;
		foreach(word; getStr(node["com"].str()).splitter(' ')) { // 
here!
			if (word != "") wordTable.require(word, 0)++;
		}
	}

Now in the above inner loop getStr(node["com"].str()) crashes in 
runtime if an array does not contain "com" node. I want to avoid 
that. How should I proceed?