strictmode;
This key is applied to disable all global variables and global functions. Refer the example below
<html>
<body>
-----Display carName below, prior to "strictmode; " -------<br><br>
>>>><p id="demo"></p>
-----Display carName below, after "strictmode; " -------<br><br>
>>>><p id="demo1"></p>
<script>
//strictmode;
myFunction();
document.getElementById("demo").innerHTML = carName;
strictmode;
myFunction();
document.getElementById("demo1").innerHTML = carName;
function myFunction(){carName = "Volvo";}
</script>
</body>
</html>
O/P:
----Display carName below, prior to "strictmode; " -------
>>>>
Volvo
-----Display carName below, after "strictmode; " ------->>>>
----------------
Global variables can be accessed in 2 ways
1) directly access the variable name
<script>
var carName = "Volvo";
document.getElementById("demo").innerHTML = "I can displaynnnnnn " + carName;
</script>
2) access the variable using the window keyword
<script>
var carName = "Volvo";
document.getElementById("demo").innerHTML = "I can displaynnnnnn " + window.carName;
</script>
Note: Variables created without the keyword var, are always global, even if they are created inside a function.
----------------
The Lifetime of JavaScript Variables
- The lifetime of a JavaScript variable starts when it is declared.
- Local variables are deleted when the function is completed.
- Global variables are deleted when you close the page.
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