Strip leading invalid characters from Schema (fix #489)

src/utils.ts

@@ -166,6 +166,8 @@ export function toSafeString(string: string) {
   return upperFirst(
     // remove accents, umlauts, ... by their basic latin letters
     deburr(string)
+      // remove leading invalid characters
+      .replace(/^[^a-zA-Z_$]+/g, '')
       // replace chars which are not valid for typescript identifiers with whitespace
       .replace(/(^\s*[^a-zA-Z_$])|([^a-zA-Z_$\d])/g, ' ')
       // uppercase leading underscores followed by lowercase

test/__snapshots__/test/test.ts.md

@@ -1804,6 +1804,22 @@ Generated by [AVA](https://avajs.dev).
     }␊
     `
 
+## leadingNumbersNames.js
+
+> Expected output to match snapshot for e2e test: leadingNumbersNames.js
+
+    `/* eslint-disable */␊
+    /**␊
+     * This file was automatically generated by json-schema-to-typescript.␊
+     * DO NOT MODIFY IT BY HAND. Instead, modify the source JSONSchema file,␊
+     * and run json-schema-to-typescript to regenerate this file.␊
+     */␊
+    ␊
+    export interface ExampleSchema {␊
+      [k: string]: unknown;␊
+    }␊
+    `
+
 ## namedProperty.js
 
 > Expected output to match snapshot for e2e test: namedProperty.js
@@ -448473,6 +448489,14 @@ Generated by [AVA](https://avajs.dev).
       a?: string;␊
       [k: string]: unknown;␊
     }␊
+    /**␊
+     * This interface was referenced by \`SafeTypeNames\`'s JSON-Schema␊
+     * via the \`definition\` "12345tartsWithManyDigits".␊
+     */␊
+    export interface TartsWithManyDigits {␊
+      a?: string;␊
+      [k: string]: unknown;␊
+    }␊
     /**␊
      * This interface was referenced by \`SafeTypeNames\`'s JSON-Schema␊
      * via the \`definition\` " 5tartsWithBlankAndDigit".␊

test/e2e/leadingNumbersNames.ts

@@ -0,0 +1,7 @@
+export const input = {
+  title: '12345Example Schema',
+  type: 'object',
+  properties: {
+
+  }
+}

test/e2e/safeTypeNames.ts

@@ -68,6 +68,11 @@ export const input = {
         a: {type: 'string'}
       }
     },
+    '12345tartsWithManyDigits': {
+      properties: {
+        a: {type: 'string'}
+      }
+    },
     ' 5tartsWithBlankAndDigit': {
       properties: {
         a: {type: 'string'}

test/testUtils.ts

@@ -17,6 +17,15 @@ export function run() {
     t.is(generateName('$Abc_123', usedNames), '$Abc_123')
     t.is(generateName('Abc-de-f', usedNames), 'AbcDeF')
 
+    // Leading invalid characters should be removed
+    t.is(generateName('2022Abc-de-f', usedNames), 'AbcDeF1')
+    t.is(generateName('555tartsWithThreeDigits', usedNames), 'TartsWithThreeDigits')
+    t.is(generateName('1234555666tartsWithManyDigits', usedNames), 'TartsWithManyDigits')
+    t.is(generateName('123-455-5666%% startsWithDigitsAndSpecialChars', usedNames), 'StartsWithDigitsAndSpecialChars')
+    t.is(generateName('123456$Abc_123', usedNames), '$Abc_1231') // there's already '$Abc_123' on line 17 above
+    t.is(generateName('654321_cbA_123', usedNames), '_CbA_123')
+    t.is(generateName('1654321_cbA_123', usedNames), '_CbA_1231') // there's already '_CbA_123' output above
+
     // Index should increment:
     t.is(generateName('a', usedNames), 'A1')
     t.is(generateName('a', usedNames), 'A2')