js: better handle multiple queries

public/partdb.js

@@ -6,6 +6,7 @@
 
 // the last search query
 var last_search = null;
+var next_search = null;
 // the collection of parts
 var parts = null;
 // last selected part
@@ -21,23 +22,35 @@ function search()
 {
 	const terms = document.getElementById('terms');
 	if (terms && terms.value && terms.value.length >= 3) {
-	} else {
-		return;
+		const current_search = '/search?terms=' + terms.value;
+		do_search(current_search);
 	}
+}
 
-	last_search = '/search?terms=' + terms.value;
-	let xhr = new XMLHttpRequest();
-	xhr.open('GET', last_search, true);
-	xhr.onload = function() {
-		if (decodeURI(this.responseURL).endsWith(last_search)) {
-			parts = JSON.parse(this.response);
-			results();
-		}
-	};
-	xhr.onerror = function() {
-		console.log("search call failed");
-	};
-	xhr.send();
+function do_search(current_search)
+{
+	if (null == last_search) { // no request running
+		last_search = current_search;
+		let xhr = new XMLHttpRequest();
+		xhr.open('GET', last_search, true);
+		xhr.onload = function() {
+			if (decodeURI(this.responseURL).endsWith(last_search)) {
+				parts = JSON.parse(this.response);
+				results();
+			}
+			last_search = null;
+			if (next_search) {
+				do_search(next_search);
+				next_search = null;
+			}
+		};
+		xhr.onerror = function() {
+			console.log("search call failed");
+		};
+		xhr.send();
+	} else {
+		next_search = current_search; // save for next search
+	}
 }
 
 function results()