tests/cases/compiler/forIn.ts(2,10): error TS2404: The left-hand side of a 'for...in' statement cannot use a type annotation. tests/cases/compiler/forIn.ts(20,4): error TS2304: Cannot find name 'k'. ==== tests/cases/compiler/forIn.ts (2 errors) ==== var arr = null; for (var i:number in arr) { // error ~ !!! error TS2404: The left-hand side of a 'for...in' statement cannot use a type annotation. var x1 = arr[i]; var y1 = arr[i]; } for (var j in arr) { // ok var x2 = arr[j]; var y2 = arr[j]; } var arr2 = []; for (j in arr2) { // ok var x3 = arr2[j]; var y3 = arr2[j]; } for (var l in arr) { // error in the body k[l] = 1; ~ !!! error TS2304: Cannot find name 'k'. }