string - Check for continuous order in array in javascript -

var userinput = prompt('enter number here'); var number = new array(userinput.tostring().split('')); if (number ????){ //checks if number in continuous stream alert(correct); } else{ alert(invalid); } 

in javascript, can @ "????" check if in continuous order/stream? how can checks order/stream after specific index in array? meaning user enters "12345678901234" pop correct, "12347678901234" pop invalid?(note there 2 7's) second part "3312345678901234" pop correct, how can implemented?

you can make function checks string stream of continuous/increasing alpha-numeric characters starting @ given index this:

function checkcontinuous(str, startindex) {     startindex = startindex || 0;     if (str.length <= startindex) {         return false;     }     var last = str.charcodeat(startindex);     (var = startindex + 1; < str.length; i++) {         ++last;         if (str.charcodeat(i) !== last) {             return false;         }     }     return true; } 

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if it's numbers , wrapping 9 0 considered continuous, it's little more complicated this:

function checkcontinuous(str, startindex) {     // make sure startindex set 0 if not passed in     startindex = startindex || 0;     // skip chars before startindex     str = str.substr(startindex);     // string must @ least 2 chars long , must numbers     if (str.length < 2 || !/^\d+$/.test(str)) {         return false;     }     // first char code in string     var last = str.charcodeat(0);     // rest of string, compare last code     (var = 1; < str.length; i++) {         // increment last charcode can compare sequence         if (last === 57) {             // if 9, wrap 0             last = 48;         } else {            // else increment             ++last;         }         // if find 1 char out of sequence, it's not continuous return false         if (str.charcodeat(i) !== last) {             return false;         }     }     // continuous     return true; } 

working demo: http://jsfiddle.net/jfriend00/rhh4b/