feat: add truncate utils

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@risc0/ui",
-  "version": "0.0.30",
+  "version": "0.0.31",
   "sideEffects": false,
   "type": "module",
   "scripts": {

utils/truncate.spec.ts

@@ -0,0 +1,52 @@
+import truncate from './truncate';
+
+describe('truncate', () => {
+  it('should truncate longer textes with a fixed length of characters in the last chunk', () => {
+    const text = '1234567890abcdefghijklmnopqrstuvwxyz';
+    const chars = 14;
+    const result = truncate(text, chars);
+    expect(result).toBe('1234567890…wxyz');
+  });
+
+  it('should truncate the text when the chars parameter is less than the length of the text', () => {
+    const text = '1234567890';
+    const chars = 5;
+    const result = truncate(text, chars);
+    expect(result).toBe('123…90');
+  });
+
+  it('should return the full text when the chars parameter is equal to the length of the text', () => {
+    const text = '1234567890';
+    const chars = 10;
+    const result = truncate(text, chars);
+    expect(result).toBe(text);
+  });
+
+  it('should return the full text when the chars parameter is greater than the length of the text', () => {
+    const text = '1234567890';
+    const chars = 11;
+    const result = truncate(text, chars);
+    expect(result).toBe(text);
+  });
+
+  it('should handle an text with an odd number of characters', () => {
+    const text = '123456789';
+    const chars = 5;
+    const result = truncate(text, chars);
+    expect(result).toBe('123…89');
+  });
+
+  it('should handle an text with only one character', () => {
+    const text = '1';
+    const chars = 1;
+    const result = truncate(text, chars);
+    expect(result).toBe(text);
+  });
+
+  it('should handle an empty text', () => {
+    const text = '';
+    const chars = 1;
+    const result = truncate(text, chars);
+    expect(result).toBe(text);
+  });
+});

utils/truncate.ts

@@ -0,0 +1,22 @@
+const MAX_LAST_CHUNK_LENGTH = 4;
+
+const truncate = (text: string, chars = 9): string => {
+  if (chars >= text.length) {
+    return text;
+  }
+
+  if (chars < MAX_LAST_CHUNK_LENGTH * 2) {
+    const firstChunk = text.slice(0, Math.max(0, Math.round(chars / 2)));
+    const lastChunk = text.slice(-Math.floor(chars / 2));
+
+    return `${firstChunk}…${lastChunk}`;
+  }
+
+  const firstChunk = text.slice(0, Math.max(0, chars - MAX_LAST_CHUNK_LENGTH));
+
+  const lastChunk = text.substr(text.length - MAX_LAST_CHUNK_LENGTH, chars);
+
+  return `${firstChunk}…${lastChunk}`;
+};
+
+export default truncate;