In front-end development, we can't avoid many arrays , There are many cases where arrays are nested or arrays need to be merged . Today, Xiao Qian will introduce how to flatten the array .

       The concept of array flattening : Arrays used to nest multiple layers “ Flatten ”, Into a one-dimensional array

       Method 1 : adopt concat Convert a two-dimensional array to a one-dimensional array

       principle : By extending the operator , Expand the inside of the array , And pass concat Concatenating two strings returns a new array .

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       Method 2 : Use the array method join And string methods split Flatten the array

       principle : adopt join Method to convert an array to a string separated by dots , In the use of split Convert the converted String into an array of strings , adopt .map Method to convert an internal string to a number type

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       Method 3 : Through regular methods and JSON.stringify Methods and array methods

       principle : First, convert the array to a string Use string matching regular rules Replace all '[' ']' It's similar to method two split It's mainly about converting strings into arrays ,map Convert a string array to a number

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       Method four : Function recursion

       principle : Judge whether the current value is an array , If it's an array, call it recursively

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       Method five : adopt reduce Method to flatten the array

       principle : Mainly through reduce In turn , Judge whether the current object is an array , If it is an array, a function recursion is performed to flatten all the arrays inside ( Similar to method four )

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       Methods six :ES6 The new method flat()

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       This article is from Qianfeng education , Reprint please indicate the source .