指定javascript字符串拆分大小

Question

I want to separete this text with split function like this. Array items should be 3 charecters.

var text = "abcdef";
var splitted = ["abc", "def"]

var text = "abcdefg";
var splitted = ["a", "bcd", "efg"]

var text = "abcdefgk";
var splitted = ["ab", "cde", "fgk"]

text split from last to first.

Answer 1

var size = 3; //specify the size here
var str = "abcdefgk" //the string you want to split

var i = str.length % 3; // modulo gets you the remaining part
var result = [str.substring(0,i)]; //create array with only first part

//for the rest, iterate over str and add chunks of length size
for(; i < str.length; i+=size){
    result.push(str.substring(i, i+size))

}
alert(result) //display the result

Answer 2

Regex solution:

var text = "abcdefg";
var regex = text.length % 3 ? '^.{'+ (text.length % 3) +'}|.{3}' : '.{3}';
var result = text.match(new RegExp(regex, 'g'));
// ["a", "bcd", "efg"]

You could also do with:

var text = "abcdefg";
var result = [text.substr(0, text.length % 3)].concat(text.substr(text.length % 3).match(/.{3}/g));

Hint : consider .match instead of .split to get the result when using regex.

Answer 3

If you want to use recursion then try this

<script type="text/javascript">
    function strSplit(str){
        var arr=[];
        dorecurSplit(str,str.length,arr,0);
        alert(arr);
    }
    function dorecurSplit(st,len,ar,x)
    {
        if(len<=0)
            return ar;
        else{
            var i=len%3;
            if(i==0)
                {
                    ar.push(st.substring(x,x+3));
                    dorecurSplit(st,len-3,ar,x+3);
                }
            else
                {
                    ar.push(st.substring(x,i));
                    dorecurSplit(st,len-i,ar,x+i);
                }
        }

    }
</script>

to call this

<button onclick="strSplit('abcdefghij')">Split it</button>

Answer 4

For the desired output, we need to use substring, since the smaller section is taken at beginning than at end. Note: we do not use slice, because negative index in slice will take characters from string from end again. So, we stick with substring to avoid that.

var str = "abcdefgh";
var len = str.length;
var res = [];

for(var i=len;i>0;i=i-3){
 res.push(str.substring(i-3,i));
}
//res array will contain the desired output now

But, if parsing should be greedy form beginning, ie {3,3,2} instead of {2,3,3} then, use the regex ( /[a-zA-Z]{1,3}/gi ) for this,which is easier and faster.For this we do not need substring. var str = "abcdef"; var result = str.match(/[a-zA-Z]{1,3}/gi); //["abc","def"]

var str = "abcdefgh";
var result = str.match(/[a-zA-Z]{1,3}/gi); //["abc","def","gh"]

var str = "abcdefg";
var result = str.match(/[a-zA-Z]{1,3}/gi); //["abc","def","g"]