diff --git a/index.html b/index.html
index 3d7cc584b81445eb9d17f4603c0a88206866b7ad..4c8967ebdc0fe4a513dbe26974a2481d94aaca90 100644
--- a/index.html
+++ b/index.html
@@ -100,7 +100,7 @@
                         <p>Choose a name for the new buffer:</p>
                         <input id="bufferName"><br>
 
-                        <p>Do you want to dissolve the layers? <input type="checkbox" id="bufferCheck"></p>
+                        <p>Do you want to dissolve the buffers? <input type="checkbox" id="bufferCheck"></p>
 
                         <button class="button" style="font-size: 25px;" onclick="makeBuffer()">Make buffer</button>
                     </div>
@@ -115,7 +115,7 @@
                             </svg>
                         </div>
 
-                        <p>Which layer do you want to remove features from:</p>
+                        <p>Which layer do you want to remove areas from:</p>
                         <select id="differenceSelect_1"></select>
 
                         <p>Which layer do you want to remove from the first one:</p>
@@ -160,7 +160,7 @@
                         <select id="extractSelect"></select>
 
                         <p>Which feature will you extract to a new layer:</p>
-                        <select id="propertySelect"></select>
+                        <select id="featureSelect"></select>
 
                         <p>Which value will you sort out:</p>
                         <select id="valueSelect"></select>
diff --git a/javascript/buffer.js b/javascript/buffer.js
index 63abc6734ead358532a95ed4d57c7835d8e1072c..fe267550ab61577388c9311071b7567da84f98ac 100644
--- a/javascript/buffer.js
+++ b/javascript/buffer.js
@@ -4,6 +4,24 @@ https://turfjs.org/docs/
 */
 
 function makeBuffer() {
+    
+    // Sjekk av faktisk og gyldig input:
+    
+    var regex_1 = /^[0-9]+$/;
+    var regex_2 = /^[a-zA-Z_0-9]+$/;
+    
+    if (document.getElementById("bufferSelect").value == "- - -") {
+        return alert("You need to choose a layer!");
+    } else if (!document.getElementById("bufferDistance").value) {
+        return alert("You need to set a distance as an integer!");
+    } else if (!document.getElementById("bufferDistance").value.match(regex_1)) {
+        return alert("You need to set a distance as an integer!");
+    } else if (!document.getElementById("bufferName").value) {
+        return alert("You need to choose a name for the new layer!");
+    } else if (!document.getElementById("bufferName").value.match(regex_2)) {
+        return alert("The new name must consist of normal letters!");
+    }
+
     var input = document.getElementById("bufferSelect").value;
     var layer = overlayMaps[input].toGeoJSON();
     var distance = parseFloat(document.getElementById("bufferDistance").value);
diff --git a/javascript/difference.js b/javascript/difference.js
index 6b9f6d3774231022efd6460327791c97b30ddd52..d0abe02bddde7812263520fd624c91643b2fc029 100644
--- a/javascript/difference.js
+++ b/javascript/difference.js
@@ -1,4 +1,19 @@
 function difference() {
+
+    // Sjekk av faktisk og gyldig input:
+
+    var regex = /^[a-zA-Z_0-9]+$/;
+
+    if (document.getElementById("differenceSelect_1").value == "- - -") {
+        return alert("You need to choose the first layer!");
+    } else if (document.getElementById("differenceSelect_2").value == "- - -") {
+        return alert("You need to choose the second layer!");
+    } else if (!document.getElementById("differenceName").value) {
+        return alert("You need to choose a name for the new layer!");
+    } else if (!document.getElementById("differenceName").value.match(regex)) {
+        return alert("The new name must consist of normal letters!");
+    }
+    
     var input1 = document.getElementById("differenceSelect_1").value;
     var layer1 = overlayMaps[input1].toGeoJSON();
     var input2 = document.getElementById("differenceSelect_2").value;
diff --git a/javascript/dissolve.js b/javascript/dissolve.js
index b81f94cdb64fe9549ba76e6059c5a1b1eb702c2d..653845ca11c6400815f843275d177a5ce8cdb17a 100644
--- a/javascript/dissolve.js
+++ b/javascript/dissolve.js
@@ -1,4 +1,17 @@
 function dissolve() {
+
+    // Sjekk av faktisk og gyldig input:
+
+    var regex = /^[a-zA-Z_0-9]+$/;
+
+    if (document.getElementById("dissolveSelect").value == "- - -") {
+        return alert("You need to choose a layer!");
+    } else if (!document.getElementById("dissolveName").value) {
+        return alert("You need to choose a name for the new layer!");
+    } else if (!document.getElementById("dissolveName").value.match(regex)) {
+        return alert("The new name must consist of normal letters!");
+    }
+
     var input = document.getElementById("dissolveSelect").value;
     var layer = overlayMaps[input].toGeoJSON();
     var name = document.getElementById("dissolveName").value;
diff --git a/javascript/extract.js b/javascript/extract.js
index 51fdfe21e169d4d4794aae405d37f720cb6cd756..9ff6b310acfe1343d478fca10306521a7dbb3271 100644
--- a/javascript/extract.js
+++ b/javascript/extract.js
@@ -2,7 +2,7 @@ document.getElementById("extractSelect").addEventListener("change", () => {
     var input = document.getElementById("extractSelect").value;
 
     if (input == "- - -") {
-        var select = document.getElementById("propertySelect");
+        var select = document.getElementById("featureSelect");
         select.innerHTML = "";
         select.add(new Option(text="- - -"));
     } else {
@@ -18,7 +18,7 @@ document.getElementById("extractSelect").addEventListener("change", () => {
             }
         }
         
-        var select = document.getElementById("propertySelect");
+        var select = document.getElementById("featureSelect");
         select.innerHTML = "";
         select.add(new Option(text="- - -"));
 
@@ -28,7 +28,7 @@ document.getElementById("extractSelect").addEventListener("change", () => {
     }
 })
 
-document.getElementById("propertySelect").addEventListener("change", () => {
+document.getElementById("featureSelect").addEventListener("change", () => {
     var input = document.getElementById("extractSelect").value;
 
     if (input == "- - -") {
@@ -37,7 +37,7 @@ document.getElementById("propertySelect").addEventListener("change", () => {
         select.add(new Option(text="- - -"));
     } else {
         var layer = overlayMaps[input].toGeoJSON();
-        var property = document.getElementById("propertySelect").value;
+        var property = document.getElementById("featureSelect").value;
 
         var values = [];
 
@@ -58,9 +58,26 @@ document.getElementById("propertySelect").addEventListener("change", () => {
 })
 
 function extract() {
+    
+    // Sjekk av faktisk og gyldig input:
+
+    var regex = /^[a-zA-Z_0-9]+$/;
+
+    if (document.getElementById("extractSelect").value == "- - -") {
+        return alert("You need to choose a layer!");
+    } else if (document.getElementById("featureSelect").value == "- - -") {
+        return alert("You need to choose a feature!");
+    } else if (document.getElementById("valueSelect").value == "- - -") {
+        return alert("You need to choose a value!");
+    } else if (!document.getElementById("extractName").value) {
+        return alert("You need to choose a name for the new layer!");
+    } else if (!document.getElementById("extractName").value.match(regex)) {
+        return alert("The new name must consist of normal letters!");
+    }
+
     var input = document.getElementById("extractSelect").value;
     var layer = overlayMaps[input].toGeoJSON();
-    var property = document.getElementById("propertySelect").value;
+    var property = document.getElementById("featureSelect").value;
     var value = document.getElementById("valueSelect").value;
     var name = document.getElementById("extractName").value;
 
@@ -90,7 +107,7 @@ function extract() {
 function resetInput() {
     fillSelect("extractSelect");
 
-    var select = document.getElementById("propertySelect");
+    var select = document.getElementById("featureSelect");
     select.innerHTML = "";
 
     var select = document.getElementById("valueSelect");
diff --git a/javascript/intersect.js b/javascript/intersect.js
index d04e02df4c5fdf6d683b0ddcdc23b517ce2bded8..100fb2aff8772e10dd02c6a1bc16b487aa3628a2 100644
--- a/javascript/intersect.js
+++ b/javascript/intersect.js
@@ -1,4 +1,19 @@
 function intersection() {
+
+    // Sjekk av faktisk og gyldig input:
+
+    var regex = /^[a-zA-Z_0-9]+$/;
+
+    if (document.getElementById("intersectionSelect_1").value == "- - -") {
+        return alert("You need to choose the first layer!");
+    } else if (document.getElementById("intersectionSelect_2").value == "- - -") {
+        return alert("You need to choose the secondt layer!");
+    } else if (!document.getElementById("intersectionName").value) {
+        return alert("You need to choose a name for the new layer!");
+    } else if (!document.getElementById("intersectionName").value.match(regex)) {
+        return alert("The new name must consist of normal letters!");
+    }
+
     var input1 = document.getElementById("intersectionSelect_1").value;
     var layer1 = overlayMaps[input1].toGeoJSON();
     var input2 = document.getElementById("intersectionSelect_2").value;
diff --git a/javascript/union.js b/javascript/union.js
index 1e38d208fe5b734cc4dc5653875461a6a431067d..3369f8a1c0bcfe3f0cf48962105709a8cf834166 100644
--- a/javascript/union.js
+++ b/javascript/union.js
@@ -1,4 +1,19 @@
 function union() {
+
+    // Sjekk av faktisk og gyldig input:
+
+    var regex = /^[a-zA-Z_0-9]+$/;
+
+    if (document.getElementById("unionSelect_1").value == "- - -") {
+        return alert("You need to choose the first layer!");
+    } else if (document.getElementById("unionSelect_2").value == "- - -") {
+        return alert("You need to choose the secondt layer!");
+    } else if (!document.getElementById("unionName").value) {
+        return alert("You need to choose a name for the new layer!");
+    } else if (!document.getElementById("unionName").value.match(regex)) {
+        return alert("The new name must consist of normal letters!");
+    }
+
     var input1 = document.getElementById("unionSelect_1").value;
     var layer1 = overlayMaps[input1].toGeoJSON();
     var input2 = document.getElementById("unionSelect_2").value;
@@ -6,12 +21,9 @@ function union() {
     var name = document.getElementById("unionName").value;
 
     // MÃ¥ konverteres fra feature collection til multipolygon:
-    var coords1 = featureCollectionToMultiPolygon(layer1);
-    var coords2 = featureCollectionToMultiPolygon(layer2);
+    var multiPolygon1 = featureCollectionToMultiPolygon(layer1);
+    var multiPolygon2 = featureCollectionToMultiPolygon(layer2);
     
-    var multiPolygon1 = turf.multiPolygon(coords1);
-    var multiPolygon2 = turf.multiPolygon(coords2);
-
     try {
         var union = turf.union(multiPolygon1, multiPolygon2);