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How does JavaScript Variable Scope work?
The scope of a variable is the region of your program in which it is defined. JavaScript variables have only two scopes.
- Global Variables − A global variable has a global scope which means it can be defined anywhere in your JavaScript code.
- Local Variables − A local variable will be visible only within a function where it is defined. Function parameters are always local to that function.
Let’s see how the scope of variables works in JavaScript.
Within the body of a function, a local variable takes precedence over a global variable with the same name. If you declare a local variable or function parameter with the same name as a global variable, you effectively hide the global variable.
Example
<html>
<body onload = checkscope();>
<script>
<!--
var myVar = "global"; // Declare a global variable
function checkscope( ) {
var myVar = "local"; // Declare a local variable
document.write(myVar);
}
//-->
</script>
</body>
</html>
Updated on 13-Jun-2020 07:41:31
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