js uses for loop to query whether a certain value exists in an array_javascript skills

It should be because IE8 does not support indexOf, so write a for loop method to determine whether it exists and return true false

function isCon(arr, val){ 
for(var i=0; i<arr.length; i++){ 
if(arr[i] == val) 
return true; 
} 
return false; 
}

Add this method in js and call the method at the calling location

window.onload = function(){ 
var arr=new Array(1,2,3,2,4,2,5,6,7,2,4,3,18,12,41,87); 
alert(isCon(arr, 8)); 
}