How to check whether an element of array exists in string in Javascript?

Question

I have an array which contains words. Also i have a string. I need to check whether an element of array exists in a string. I've tried but without success. It's not working.

function inputValidate() {
    var val = document.getElementById("title");
    var keyWords = ["kerak", "nega", "qanday", "qanaqa", "nimaga", "mi"];
    val.value.trim();
    len = val.value.length - 1;
    lastS = val.value.slice(len);

    if (lastS != "?") {
        document.getElementById("error").innerHTML = "Savol so`roq belgisi bilan tugashi lozim.";
    } else {
        document.getElementById("error").innerHTML = " ";
        document.getElementById("error").style.color = "red";
    }

    for (i = 0; i < keyWords.length; i++) {
        if (val.indexOf(keyWords[i]) != -1) {
            document.getElementById("error2").innerHTML = "Gapingizga so`roq gapga o`xshamadi ";
        } else {
            document.getElementById("error2").innerHTML = " ";
        }
    }
}

http://codepen.io/anon/pen/vOMWyQ

what is the value in title? Also you will end up matching words inside of words. — epascarello
– epascarello, Commented Aug 13, 2015 at 15:01
My bad, still i = 6 instead of i<keyWords.length is an error — sander
– sander, Commented Aug 13, 2015 at 15:03

danillouz · Accepted Answer · 2015-08-13 15:53:00Z

1

I need to check whether an element of array exists in a string.

// The elements you want to be checked in a certain string.
var KEYWORDS = [ 'world' ];

/**
 * Checks if an element of a keyword array occurs in a certain text string.
 *
 * @param {Array}  keywords   - contains keyword strings
 * @param {String} textString - text string to be checked
 *
 * @return {Boolean} denotes if a match was found.
 */
var keywordExistsInString = function (keywords, textString) {
    // Split the text string for easy matching.
    var words = textString.slice(/\s*\b\s*/);

    // Only interested if ONE of the keywords matches.
    // NOTE: if all keywords must match use 'every()' instead of 'some()'.
    return keywords.some(function (keyword) {

        // Use 'bitwise not' to determine a match.
        // Double negate to convert to a Boolean.
        return !!~words.indexOf(keyword);
    });
};

keywordExistsInString(KEYWORDS, 'hello world'); // true
keywordExistsInString(KEYWORDS, 'hello');       // false

edited Aug 13, 2015 at 15:53

answered Aug 13, 2015 at 15:29

danillouz

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4 Comments

Power Over a year ago

what does (/\s*\b\s*/) mean? Could you explain please

danillouz Over a year ago

@Sardor \b splits on word boundaries and \s* matches zero or more white space characters, including space, tab, form feed, line feed. For more info check MDN

Andreas Over a year ago

Why the "cryptic" return !!~words.indexOf(keyword) instead of simply return words.indexOf(keyword) > -1

danillouz Over a year ago

@Andreas in my opinion the ~ operator is more elegant than > 1. The double negation is shorter that using Boolean(). But on the other hand, when using > 1, the conversion to a Boolean does become superfluous. I guess you might be right that it could be a little bit cryptic though, especially when not dropping comments. I guess it's a matter of taste :)

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