substr() not behaving as expected to concatenate string javascript

Question

I'm trying to create a function that returns a string in camel case capitalizing each letter where there is a hyphen. i.e. "this-should-be-camel-case" would return "thisShouldBeCamelCase".

I've changed to first letter of each word to capital and removed to hyphen but can't get the completed sentence to return. I've tried playing with substr and substring to no avail, not sure if they're what I want to be using for the task.

What should I be using to return the sentence in camel case ? How do I do this ? Thanks

function camelCaseIt(str) {

for(var i = 0; i < str.length; i++) {

    if(str[i] == '-') {
        var chgLtr = str[i] = '';
        var uprCase = str[i+1].toUpperCase();

    }
}
return str;
}

alert(camelCaseIt('this-should-be-camel-cased'));

AlliterativeAlice · Accepted Answer · 2014-01-02 21:01:04Z

3

This can be accomplished fairly simply with a regular expression:

function camelCaseIt(str) {
    return str.replace(/-([a-z])?/g, function(v) { return (v.length > 1 ? v[1].toUpperCase() : ''); });
}

answered Jan 2, 2014 at 21:01

AlliterativeAlice

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1 Comment

jJ' Over a year ago

nice, or perhaps even simpler expr.: str.replace(/-(\w)/g, function (m, c) { return c.toUpperCase(); })

Brian S · Accepted Answer · 2014-01-02 21:04:40Z

Indexing the characters of a string as though it's a character array may not work in all browsers (it's nonstandard behavior prior to EMCAScript 5). While it's correct for browsers compatible with the newest JS standard, you shouldn't use that syntax if you want to support older browsers. (And even in EMCAScript 5, you can't do for example str[i] = ''.)

function camelCaseIt(str) {
    // create an array ['this', 'should', 'be', 'camel', 'cased']
    var parts = str.split('-');

    // start at i = 1 to skip the first word
    for (var i = 1; i < parts.length; i++) {
        // create an array ['s', 'h', 'o', 'u', 'l', 'd']
        var ltrs = parts[i].split('');
        // ltrs is now ['S', 'h', 'o', 'u', 'l', 'd']
        ltrs[0] = ltrs[0].toUpperCase();
        // parts is now ['this', 'Should', 'Be', 'Camel', 'Cased']
        parts[i] = ltrs.join('');
    }

    // return thisShouldBeCamelCased
    return parts.join('');
}

newfurniturey · Accepted Answer · 2014-01-02 21:02:07Z

1

In your function, you're returning the original (unmodified string). Instead, you should be building a separate (new) string and returning that:

function camelCaseIt(str) {
    var modifiedString = '';
    for(var i = 0; i < str.length; i++) {
        if(str.charAt(i) == '-') {
            // hyphen; if there is another character, upper-case it and append
            if ((i + 1) < str.length) {
                modifiedString = str.charAt(i + 1).toUpperCase();
            }
        } else {
            // normal character; append it as-is
            modifiedString += str.charAt(i);
        }
    }
    return modifiedString;
}

However, you should be able to accomplish the same thing with a simple regex:

str = str.replace(/-([a-z])/g, function (match) {
    return match[1].toUpperCase();
});

answered Jan 2, 2014 at 21:02

newfurniturey

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1 Comment

newfurniturey Over a year ago

You could also, if you want array-style access, use str.split('-') to produce an array instead of using str.charAt().

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