slice()、substr()、substring()的结果

>> var str="i love you" 
>> str.slice(1) 
" love you" 
>> str.substr(1) 
" love you" 
>> str.substring(1) 
" love you" 
>> str.slice(1,4) 
" lo" 
>> str.substr(1,4) 
" lov" 
>> str.substring(1,4) 
" lo"