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testvar[1] is the value of that array index, which is the number 2. Numbers don't have a length property, and you're checking for 2.length which is undefined. If you want the length of the array just check testvar.length
The array.length condition checks whether the variable's length property evaluates to a truthy value. Because the previous condition already established that we are indeed dealing with an array, more strict comparisons like array.length != 0 or array.length !== 0 are not required here. The pragmatic approach
When you call Array.apply with an array or an object with a length property Array is going to use the length to explicitly set each value of the new array. This is why Array(5) gives an array of 5 elisions, while Array.apply(null, Array(5)) gives an array of 5 undefined's.
Here is an example where I split an array into chunks of 2 elements, simply by splicing chunks out of the array until the original array is empty. const array = [86,133,87,133,88,133,89,133,90,133]; const new_array = []; const chunksize = 2; while (array.length) {. const chunk = array.splice(0,chunksize);
const result = new Array(3) // result = [undefined , undefined , undefined] If you iterator only returns 2 values, or the values are filtered after the take(3) command and 1 of your values is removed the array would look like //result = [1 , 1 , undefined] so to truncate the array of empty elements you can use
If you have to think what the compiler is doing behind, knowing V8 is written in C++ and C++ is typed, the array length which is a number is treated as a boolean expression so I would say that in some cases it does the equivalent of Boolean(array.length) when the > 0 is not present. There are a lots of different values that can be true or false ...
How to split a long array into smaller arrays, with JavaScript (27 answers) Closed 9 years ago . How to split an array (which has 10 items) into 4 chunks, which contain a maximum of n items.
Determining the length of an array is a fundamental operation in JavaScript. We will explore multiple approaches to find the length of an array. Please refer WebDevLearners for more details. Approach 1. Using length Property The most straightforward and commonly used method to find the length of an array is by accessing its length property ...
5663. Ways to clear an existing array A: Method 1. (this was my original answer to the question) A = []; This code will set the variable A to a new empty array. This is perfect if you don't have references to the original array A anywhere else because this actually creates a brand new (empty) array. You should be careful with this method ...
0. The first check: array === [] checks if both arrays are of the same type (check) and if they are the same array. The reason the result is false is because: although they are both an array. and although they are both empty, they are not the same arrays (array is stored in location A, and [] is stored somewhere else.