Check if value contains certain string

Question

I want to check if the selected contains "color-" or "image-" and show the appropriate .

Please post relevant code samples. What do you mean by `selected contains` ? — Rajaprabhu Aravindasamy, Nov 23 '13 at 21:39

score 1 · Accepted Answer · answered Nov 23 '13 at 21:44

I think what you ment was really to check if some string contains given substring. You can do the following:

childValue.indexOf('color-');

If the substring is present it will return the index where this substring appeared, if not it will return -1.

score 1 · Answer 2 · edited May 23 '17 at 10:31

1

This issue has not really anything to do with jQuery but rather with JavaScript itself. The "most clean" way would be to extend the String prototype in JavaScript with a startsWith-procedure:

if (typeof String.prototype.startsWith != 'function') {
  String.prototype.startsWith = function (str){
    return this.slice(0, str.length) == str;
  };
}

Next you can use the new procedure with any string you want:

if(childValue.startsWith ("color-")){
    //show pickColor div
}

Should you discover a better method to compare the beginning of a string you can simply change the prototype declaration once. That's far easier than changing every occurence of whatever you choose to use in the rest of your code.

Sources:

Javascript StartsWith

edited May 23 '17 at 10:31

Community

1
1

answered Nov 23 '13 at 21:49

samvv

1,934
1
18
26

But! Now I'm confused, `str.indexOf('color-') === 0` does exactly the same thing ? – adeneo Nov 23 '13 at 21:56
Hey adeneo, yes but apparently this.slice(0, str.length) == str; is a lot faster then str.indexOf('color-') === 0 http://stackoverflow.com/a/646643/1173521 – samvv Nov 23 '13 at 22:53

score 0 · Answer 3 · edited Nov 23 '13 at 21:47

0

Maybe use something like this?

$(selectChild).on('change',function(){
    var childOption = $("option:selected", this);

    if (childOption.is('[value^=color]')) {
        //show pickColor div
    } else if (childOption.is('[value^=image]')) {
            //show Upload div
    }

});

http://api.jquery.com/attribute-starts-with-selector/

edited Nov 23 '13 at 21:47

megawac

10,953
5
40
61

answered Nov 23 '13 at 21:45

Justin Lee

909
4
9
19

Check if value contains certain string

3 Answers3