You can try the following below code.
var rank1 = 0
var rank2 = 0
var rank3 = 0
var rank4 = 0
const array1 = ['rank1','rank1','rank1','rank3']
array1.forEach( function( item, i ) {
eval( item + '+= ' + 1 + ';');
} );
console.log(rank1, rank3);
2
solved For-each in a array Javascript [duplicate]