Frequency Measuring Techniques for Competitive Programming | Javascript program to count frequencies of array items ; Create an array to store counts . The size of array is limit + 1 and all values are initially 0 ; Traverse through string characters and count frequencies ; Driver Code
let limit = 255 ; function countFreq ( str ) { let count = new Array ( limit + 1 ) ; for ( let i = 0 ; i < count . length ; i ++ ) { count [ i ] = 0 ; } for ( let i = 0 ; i < str . length ; i ++ ) count [ str [ i ] . charCodeAt ( 0 ) ] ++ ; for ( let i = 0 ; i <= limit ; i ++ ) { if ( count [ i ] > 0 ) document . write ( String . fromCharCode ( i ) + " " + count [ i ] + " " ) ; } } let str = " " ; countFreq ( str ) ;