A brief discussion on the difference between String() and .toString() in JS

We know that both String() and .toString() can be converted to string types, but there are still differences between String() and .toString()

1. .toString() can convert all data as a string, but exclude null and undefined

For example, convert false to string type

<script>
  var str = false.toString();
  console.log(str, typeof str);
</script>

The returned result is false, string

See if null and undefined can be converted to string

<blockquote style="margin-right: 0px;" dir="ltr"><pre class="html" name="code"><script>
  var str = null.toString();
  console.log(str, typeof str);
</script>

As a result, the program reported an error

<script>
  var str = undefined.toString();
  console.log(str, typeof str);
</script>

The program also reported an error

.toString() You can write a number in the brackets, representing the base, corresponding to the base string

Binary: .toString(2);

Octal: .toString(8);

Decimal: .toString(10);

Hex: .toString(16);

2. String() can convert null and undefined into strings, But there is no way to convert into a string

For example, if you convert null to a string

<script>
  var str = String(null);
  console.log(str, typeof str);
</script>

, the result returned is null, string

convert undefined to a string

<script>
  var str = String(undefined);
  console.log(str, typeof str);
</script>

The result returned is undefined, string