JS get array subscript through array content

js Get the array subscript through the array content

demand ： By knowing something in the array , Then delete the array through this content , Is to find the subscript of the array by looping , Then take it to delete .

Method 1：js How to write it

var arr = [1, 1, 2, 12, 3, 23, 5, 6, 45]; // Array 
var k = 12;// To find the contents of the array 
var c = [];// The subscript of the array obtained by content 
// Get subscript 
for (var i = 0; i < arr.length; i++) {
    
    if (k == arr[i]) {
    
        c.push(i)
    }
}
console.log(c)  // [3]

Method 2：ES6 Of map grammar ,

Although code introduction , But you can only find the first , Some places just need the first one , If there is a repetition , You can use the first method .

var arr = [23,45,312,3213,53,23]
var index = arr.map(item => item).indexOf(23)
console.log(index)  // 0