New: Support Definite Assignment (fixes eslint#424)

Author: azz

lib/convert.js

@@ -658,6 +658,10 @@ module.exports = function convert(config) {
                 init: convertChild(node.initializer)
             });
 
+            if (node.exclamationToken) {
+                result.exclamationToken = true;
+            }
+
             if (node.type) {
                 result.id.typeAnnotation = convertTypeAnnotation(node.type);
                 fixTypeAnnotationParentLocation(result.id);
@@ -859,6 +863,10 @@ module.exports = function convert(config) {
                 result.key.optional = true;
             }
 
+            if (node.exclamationToken) {
+                result.exclamationToken = true;
+            }
+
             if (result.key.type === AST_NODE_TYPES.Literal && node.questionToken) {
                 result.optional = true;
             }

tests/fixtures/typescript/basics/class-with-definite-assignment.src.ts

@@ -0,0 +1,3 @@
+class X {
+  a!: string;
+}

tests/fixtures/typescript/basics/var-with-definite-assignment.src.ts

@@ -0,0 +1,3 @@
+const x!: string;
+var y!: number;
+let z!: object;