Learning Salesforce Lightning Application Development

Strict mode enforcement in Locker Service

Locker Service automatically enforces ES5 strict mode for the JavaScript. If you write JavaScript that is not valid in strict mode, you will see unexpected errors. Let's take a look at some of the best practices that one must follow for the JavaScript code in controllers and helper files:

• Using a variable without declaring it is not allowed. Suppose that you declare a variable as follows:

a = component.set("v.name",'Test'); 

 This is invalid; instead, use the var keyword. The correct syntax is as follows:

var a = component.set("v.name",'Test');

• Using an object without declaring it is also not allowed:

x = {x:4, y:20};      // This will cause an error

   The fix for the preceding is as follows:

var ...