JavaScript array usage experience

Josh left a comment in one of my previous posts, pointing out that some minor errors exist in CSSpropertywatchercomponent. This is a jQuery plug-in that stores CSS attributes in arrays, tracking the changes of these values. When the CSS property value changes, an event is thrown, and you can handle the event accordingly. My mistake is that Josh left a comment in my previous post, pointing out that some minor errors exist in CSSpropertywatchercomponent. This is a jQuery plug-in that stores CSS attributes in arrays, tracking the changes of these values. When the CSS property value changes, an event is thrown, and you can handle the event accordingly.
　　
My error is how to define an array:
　　
Vardata = {
　　
Props: props. split (","),
　　
Func: func,
　　
Vals: [props. split (","). length],
　　
ItvlId: itId
　　
};
　　
This Code creates an array of specific lengths, but the results are obviously not the same as I expected. In fact, this array only contains one element, which is the value of length. to initialize the array, the correct method should be as follows:
　　
Vals: newArray (props. split (","). length)
　　
But why is the plug-in running properly even if the method I previously defined is wrong? Because JavaScript can dynamically create an Array Based on the Value assignment without pre-initialization, it can run normally even if the definition method is incorrect.
　　
$.Each(data.props,function(iction{data.vals? I =cancel.css (data. props [I]);});
　　
This code traverses the props array and dynamically creates a new array by assigning values to the corresponding index of the vals array.
　　
The JavaScript array can be automatically adjusted based on the assigned value, for example, the following example:
　　
Varar = []
　　
Ar [2] = 1;
　　
Debugger;
　　
The length of this array is 3, just like an initialized array. All array objects without assignment will be defined as undefined.
　　
JavaScript can automatically re-adjust the size of the array, which is really great, but it may be possible to set a fixed size in advance, which can avoid frequent internal resizing of the array. Assigning values to an existing element is much faster than re-adjusting the size before each assignment.
　　
This automatic resizing mechanism makes it easier to see out-of-bounds arrays (outofboundsarray) and to find out more. Pay more attention to similar situations.