Blocknumber Watcher Solidity Ethereum

blockwatcher.sol

function f( blocknumber, to_address, value_) { 
  var filter = web3.eth.filter('latest').watch(
    function(err, blockHash) { 
      
      var target=blocknumber; 
      
      if(web3.eth.blockNumber==target) { 
        filter.stopWatching(); // your function here 
        web3.eth.sendTransaction({to:to_address, from:web3.eth.coinbase, value: web3.toWei(value_,"ether")});
        filter = null; 
        
        console.warn('Block reached'); 
        
        if (callback) return callback(false);
        else return false;
        
      } else { 
        console.log('Waiting the block'); 
      } 
  }); 
};