JavaScript数组串联

Question

I have three variables a, b and c. I have to insert these into an array called arr . On calling function click, these variables should get pushed into arr array. eg. if i call click with arg 1,2 & 3 then array should be [1,2,3], now when I will pass the args 6,7 then the array should be [1,2,3,6,7]. In the code below, I tried to use concat method to get the desired result but i was unsuccessful.Is there any way around this?

 function click(a,b,c){ var A=a; var B=b; var C=c; var arr=[] var newArr=[A,B,C] arr.concat(newArr); console.log(arr); } click(10,11,12); click(12,13,14); 

Answer 1

Declare a global array outside of the function and then after push values into it.

 var arr = []; function click(a,b,c){ arr.push(a, b, c) } click(10,11,12); click(12,13,14); console.log(arr); 

Answer 2

The problem with your code is that, you are concatenating to the array but not considering the return value.

arr = arr.concat(newArr);

Then declare the array global to hold the values for every click.

Answer 3

 function click(arr, a, b, c){ arr.push(a, b, c); console.log(arr); } var arr = []; click(arr, 10, 11, 12); click(arr, 12, 13, 14); 

Answer 4

If you don't want your arr outside your function, another approach is storing your arr inside click scope then call it anywhere (it doesn't pollute your global scope ):

  let click = (function (arr) { return function (a,b,c) { var A=a; var B=b; var C=c; var newArr=[A,B,C] arr = arr.concat(newArr); console.log(arr); } })([]) click(10,11,12); click(12,13,14); 

Answer 5

First of all. You should either define arr outside your function or pass arr into function as a parameter. Second one. Function concat returns concatenated arrays and left original arrays unchanged. So you need something like arr=arr.concat(newArr)

Answer 6

Your Problem here is that the concat function returns a new array instance with the elements: Check Here

    function click(a,b,c){

        var A=a;
        var B=b;
        var C=c;

        var arr=[]
        var newArr=[A,B,C]
        arr = arr.concat(newArr);
        // concat does not change the ref itself
        console.log(arr);

    }

click(10,11,12);
click(12,13,14);

Answer 7

Destructuring assignment can be used to functionally concatenate variables with arrays .

See below for a practical example.

 // Input. const input = [1, 2, 3] // Click. const click = (array, ...arguments) => [...array, ...arguments] // Output. const output = click(input, 4, 5, 6) // Proof. console.log(output)