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This article introduces the knowledge of "analyzing the reading speed of js objects". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

1. Accessing literals and local variables is the fastest, while accessing array elements and object members is relatively slow. When you access object members, you search on the prototype chain just like the scope chain.

2. If the member found is too deep in the prototype chain, the access speed will slow down.

Therefore, it is necessary to minimize the number of searches and nesting depth of object members.

Instance / / perform two object member lookups function hasEitherClass (element, className1, className2) {return element.className = className1 | | element.className = className2;} / / optimize. If this variable does not change, you can use a local variable to save the found content function hasEitherClass (element, className1, className2) {const currentClassName = element.className; return currentClassName = className1 | | currentClassName = className2;}

Content extension:

Operational performance problems of js objects

The longer the 1 string, the more time it takes to use str+= "xxx" (almost exponentially).

When there are only 400 elements in the object array, the access time to the properties and methods of each element is reached.

For each property or method 1 tick 4 Ms! If an element has 10 attributes, then a traversal of the array takes at least 1 second.

The operation of FileSystem, especially the operation of write, is almost proportional to the square of the length of the string to be written.

4 do not use self-defined methods for string manipulation, especially substitution and search, comparison

I don't know much about regular expressions. When I use custom functions, I find that in the traversal mentioned in 2) above,

Custom functions take up to 80% of the total time!

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