javascript check if all values in array are the same code example

Example 1: check if array has same values javascript

const allEqual = arr => arr.every(v => v === arr[0]);
allEqual([1,1,1,1]);  // true

Example 2: javascript every

const age= [2,7,12,17,21];
age.every(function(person){
return person>18;
});  //false

//es6
const age= [2,7,12,17,21];
age.every((person)=> person>18);  //false