diff --git a/js/src/select.js b/js/src/select.js
index 7d5bac0..5804ceb 100644
--- a/js/src/select.js
+++ b/js/src/select.js
@@ -64,16 +64,16 @@ export default class uSelect {
     }
     this.hasAllOption = true;
     const index = this.hasHead ? 1 : 0;
-    this.element.add(new Option(this.allText, 'all'), index);
+    this.element.add(new Option(this.allText, uSelect.allValue), index);
   }
 
   hideAllOption() {
     this.hasAllOption = false;
-    this.remove('all');
+    this.remove(uSelect.allValue);
   }
 
   addHead() {
-    const head = new Option(this.headText, '0', true, true);
+    const head = new Option(this.headText, uSelect.headValue, true, true);
     head.disabled = true;
     this.element.options.add(head, 0);
   }
@@ -115,10 +115,18 @@ export default class uSelect {
       this.addHead();
     }
     if (this.hasAllOption) {
-      this.element.add(new Option(this.allText, 'all', false, selected === 'all'));
+      this.element.add(new Option(this.allText, uSelect.allValue, false, selected === uSelect.allValue));
     }
     for (const option of options) {
       this.element.add(new Option(option.listText, option.listValue, false, selected === option.listValue));
     }
   }
+
+  static get allValue() {
+    return 'all';
+  }
+
+  static get headValue() {
+    return '0';
+  }
 }
diff --git a/js/test/select.test.js b/js/test/select.test.js
index a5b96dc..2d11e5a 100644
--- a/js/test/select.test.js
+++ b/js/test/select.test.js
@@ -67,7 +67,7 @@ describe('Select tests', () => {
     expect(select.element.options[0].defaultSelected).toBe(true);
     expect(select.element.options[0].selected).toBe(true);
     expect(select.element.options[0].text).toBe(head);
-    expect(select.element.options[0].value).toBe('0');
+    expect(select.element.options[0].value).toBe(uSelect.headValue);
   });
 
   it('should construct class instance and set options', () => {
@@ -119,7 +119,7 @@ describe('Select tests', () => {
     expect(select.element.options[0].defaultSelected).toBe(true);
     expect(select.element.options[0].selected).toBe(true);
     expect(select.element.options[0].text).toBe(head);
-    expect(select.element.options[0].value).toBe('0');
+    expect(select.element.options[0].value).toBe(uSelect.headValue);
     expect(select.element.options[1].disabled).toBe(false);
     expect(select.element.options[1].defaultSelected).toBe(false);
     expect(select.element.options[1].selected).toBe(false);
@@ -143,7 +143,7 @@ describe('Select tests', () => {
     expect(select.element.options[0].defaultSelected).toBe(true);
     expect(select.element.options[0].selected).toBe(false);
     expect(select.element.options[0].text).toBe(head);
-    expect(select.element.options[0].value).toBe('0');
+    expect(select.element.options[0].value).toBe(uSelect.headValue);
     expect(select.element.options[1].disabled).toBe(false);
     expect(select.element.options[1].defaultSelected).toBe(false);
     expect(select.element.options[1].selected).toBe(false);
@@ -179,7 +179,7 @@ describe('Select tests', () => {
     select.setOptions(options, options[1].listValue);
     // then
     expect(select.element.options.length).toBe(3);
-    expect(select.element.options[0].value).toBe('all');
+    expect(select.element.options[0].value).toBe(uSelect.allValue);
     expect(select.element.options[0].text).toBe(allText);
     expect(select.element.options[2].selected).toBe(true);
   });
@@ -195,7 +195,7 @@ describe('Select tests', () => {
     select.showAllOption(allText);
     // then
     expect(select.element.options.length).toBe(3);
-    expect(select.element.options[0].value).toBe('all');
+    expect(select.element.options[0].value).toBe(uSelect.allValue);
     expect(select.element.options[0].text).toBe(allText);
     expect(select.element.options[2].selected).toBe(true);
     // when
@@ -219,9 +219,9 @@ describe('Select tests', () => {
     select.setOptions(options, options[1].listValue);
     // then
     expect(select.element.options.length).toBe(4);
-    expect(select.element.options[0].value).toBe('0');
+    expect(select.element.options[0].value).toBe(uSelect.headValue);
     expect(select.element.options[0].text).toBe(head);
-    expect(select.element.options[1].value).toBe('all');
+    expect(select.element.options[1].value).toBe(uSelect.allValue);
     expect(select.element.options[1].text).toBe(allText);
     expect(select.element.options[3].selected).toBe(true);
   });
@@ -237,7 +237,7 @@ describe('Select tests', () => {
     select.showAllOption(allText);
     // then
     expect(select.element.options.length).toBe(4);
-    expect(select.element.options[1].value).toBe('all');
+    expect(select.element.options[1].value).toBe(uSelect.allValue);
     expect(select.element.options[1].text).toBe(allText);
     expect(select.element.options[3].selected).toBe(true);
     // when