Javascript-questions about Array. prototype. slice. call and Array. prototype. concat. call

If you want to convert the dom set obtained through getElementsByTagName to a real array, you may not understand the result (different from what you expected). The test code is as follows: runjs. cncodei517birf wants to convert the dom set obtained through getElementsByTagName into a real array, which is a bit confusing for their results (different from what they expected). The test code is as follows:
Http://runjs.cn/code/i517birf

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The test code is as follows:
Http://runjs.cn/code/i517birf

Concat if all the following parameters are arrays (including this), it is the link array to return a new array. No, it is only to make these variables into an array.
Splice needs to delete certain items in this, while the returned value of getElementByTagName is read-only and cannot be deleted.
Http://zonxin.github.io/post/2015/07/javascript-array-prototype

Concat is with parameters, so yes

Array. prototype. concat. call (aLi, [])