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What does this initialization of a variable stand for:
var variable = variable || {} ;
How and when should it be used?
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JavaScript variables are containers for storing data values. In this example, x, y, and z, are variables, declared with the var keyword: Before 2015, using the var keyword was the only way to declare a JavaScript variable.
And here’s what’s happening in the example above: var is the keyword that tells JavaScript you’re declaring a variable. x is the name of that variable. = is the operator that tells JavaScript a value is coming up next. 100 is the value for the variable to store.
Variable names are pretty flexible as long as you follow a few rules: Start them with a letter, underscore _, or dollar sign $. After the first letter, you can use numbers, as well as letters, underscores, or dollar signs. Don’t use any of JavaScript’s reserved keywords.
var answer = 'Yes I am!'; Creating a variable in JavaScript is called "declaring" a variable. You declare a JavaScript variable with the var keyword: After the declaration, the variable has no value (technically it has the value of undefined ). To assign a value to the variable, use the equal sign:
That line of code does the following:
IF variable is not defined (or has a falsey value) THEN set it to an empty object.
ELSE do nothing (technically speaking, variable gets assigned to itself)
In other words variable will be converted to an empty object if it is any of the following:
See toBoolean for the spec's definition of falsey values.
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If variable is undefined or false, it initializes it to an empty object.
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It is to test if variable is initialized. If not, it initializes variable as an empty object. If it does exist, it does nothing, (technically assigns variable to itself).
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