As we saw, arrays can have several dimensions, which means that an array element can contain an array, whose elements can contain arrays, etc. I recommend using $.ajax() and specifying the dataType as JSON, or using $.getJSON(). It sounds like the data structure is confusing :-) If you have an object with unknown/random property names, you can't really access a specific property without knowing the name. The problem most likely is that the value is undefined at some point in the components lifecycle (you're probably loading it asynchronously). Creating an Array Using an array literal is the easiest way to create a JavaScript Array. I ask because when you find yourself trying to circumvent one of the most basic characteristics of a programming language, odds are good there's a better way to do what you're trying to do. The Basic For Loop. You are going to need be be defensive in the way that you reference your property. Looping Through an Array. I want to create an array whose indexing starts from 1 instead. Calling Array(N) results in a RangeError, if N is a non-whole number whose fractional portion is non-zero. let arr = Array (9.3) // RangeError: Invalid array length. The syntax to access an array member This means that array indexes start at 0 and go up to the number of elements, minus 1. It's not like an array where you can access a value by index ("pick the first value"). An “indexed” array is one where the index must be an integer, and you access its elements using its index as a reference. You could use a computed property Here’s an example of an indexed array: Here’s an example of … We can loop through the entirety of the array with the for keyword, taking advantage of the length property. So, our array of four elements has indexes from 0 to 3. Here is an example that demonstrates $.ajax() and shows you how to access the returned values in an array. By default the indexing of every JavaScript array starts from 0. As we can see data is an object, hence we can access its properties using dot notation. It would help to know what your AJAX request looks like. If your code needs to create arrays with single elements of an arbitrary data type, it is safer to use array … JavaScript for loops iterate over each item in an array. In the above example, we removed seahorse from the array, and pushed a new value into index 3. JavaScript arrays are zero based, which means the first item is referenced with an index of 0. The following example illustrates this behavior. – Strille Oct 3 '13 at 9:04 An array can hold many values under a single name, and you can access the values by referring to an index number. Remember that the index values start at 0, not 1. Referencing items in arrays is done with a numeric index, starting at zero and ending with the array length minus 1. 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