Delete default value of an input text on click

The following example will delete the default value on onFocus event and fill up the value Vice Versa.

<!DOCTYPE html>
<html>
<head>
<title>Clear ans Show Values</title>
</head>
<body>

<form action="submitPage.php">

  <input type="text" value="Search" name="SearchField" id="SearchField"
 onblur="if (this.value == '') {this.value = 'Search';}"
 onfocus="if (this.value == 'Search') {this.value = '';}" />
  <input type="submit" value="Find">
  
</form>

</body>
</html>