如何找到数组元素的索引

Question

var styles = ['btx btx1', 'btx btx2', 'btx btx3', 'btx btx4'];

$('#mst').on('click', function(){
    let a = $('#btx').attr('class');
    console.log(a);  // `btx btx2`
    let x = styles.findIndex(a);
    console.log(x);  // error
});

error - Uncaught TypeError: btx btx2 is not a function

I'm expecting 1 as the result

Answer 1

Use indexOf:

$('#mst').on('click', function(){
   let a = $('#btx').attr('class');
   console.log(a);  // `btx btx2`
   let x = styles.indexOf(a);
   console.log(x);  // error
});

Answer 2

If you want to use findIndex() , the params must be function instead of a specific item.

Syntax

array.findIndex(function(currentValue, index, arr), thisValue)

 var styles = ['btx btx1', 'btx btx2', 'btx btx3', 'btx btx4']; let a = 'btx btx2'; let x = styles.findIndex(function(currentValue, index, arr){ return currentValue === a; }); console.log(x);

Or use indexOf()

The indexOf() method searches the array for the specified item , and returns its position.

 var styles = ['btx btx1', 'btx btx2', 'btx btx3', 'btx btx4']; let a = 'btx btx2'; let x = styles.indexOf(a); console.log(x);