b1背后的邏輯是什么？b1:b2在if條件下的編碼？

1.Here是任務。

聲明一個函數或類似| |，但不使用|operator.?/**

1. @參數{any}？？？-第一個操作數
2. @參數{any}？？？-第二個操作數
3. @按順序將| |運算符應用于給定的操作數時，返回{any}相同的結果

2.Here是我嘗試過的（實際上人們給了我關于返回b1的建議？b1:b2。但我無法理解，也沒有在網上找到正確的解釋。

function or(b1, b2) {
  if (b1 == false && b2 == false) return false;
  else return b1 ? b1 : b2;
}

3.Here是編碼測試，上面的代碼通過了所有測試。但有誰能告訴我b1的邏輯嗎？b1:b2。我是初學者，請幫幫我！

//TEST 1

actual = or("bananas", false);

expected = "bananas";

if (actual === expected) {
  console.log("Yay! Test PASSED.");
} else {
  console.error("Test FAILED. Keep trying!");
  console.log("    actual: ", actual);
  console.log("  expected: ", expected);
}

//TEST 2

actual = or("", "bananas");

expected = "bananas";

if (actual === expected) {
  console.log("Yay! Test PASSED.");
} else {
  console.error("Test FAILED. Keep trying!");
  console.log("    actual: ", actual);
  console.log("  expected: ", expected);
}

//TEST 3

actual = or(true, true);

expected = true;

if (actual === expected) {
  console.log("Yay! Test PASSED.");
} else {
  console.error("Test FAILED. Keep trying!");
  console.log("    actual: ", actual);
  console.log("  expected: ", expected);
}

//TEST 4

actual = or(true, false);

expected = true;

if (actual === expected) {
  console.log("Yay! Test PASSED.");
} else {
  console.error("Test FAILED. Keep trying!");
  console.log("    actual: ", actual);
  console.log("  expected: ", expected);
}