Difficulty converting an Array of strings toLowerCase and adding to my function. Javascript

Question

I have a function that searches through an array of strings. It works perfectly, except for the fact that its case sensitive. I need it to be case insensitive.

The easiest way would be to make the function convert the array to lowercase, so when the function performs a search through the array, it is able to find it, regardless of its case.

I have tried adding var array_name_tolowercase = array_name.toLowerCase(); within my function so that when the function is called, it can work on all arrays; if needed.

Im sorry I haven't made myself clear at all, if this is the case, please let me know and I will try my best to re-explain. Thanks in advance!

Show us the code for your function so we can advise how to make it case insensitive. — jfriend00
– jfriend00, Commented Nov 9, 2011 at 22:42

Bridge · Accepted Answer · 2012-11-29 14:53:40Z

21

Easiest way is to JOIN the mixed-case array into a string, lowercase it, then SPLIT the string back into an array.

Examples:

var tmp = mcArray.join('~').toLowerCase()
var lcArray = tmp.split('~')

edited Nov 29, 2012 at 14:53

Bridge

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answered Nov 29, 2012 at 14:34

Tony

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2 Comments

Greg Over a year ago

What happens if any of the array items contains '~' ?

LukeS Over a year ago

Pretty silly... obviously that would mess up the logic. This is assuming "~" is a safe character. You could use any other character.

James Allardice · Accepted Answer · 2011-11-09 22:43:59Z

7

You will need to convert the elements of the array to lower case, not the Array object itself. I don't know exactly what happens inside your function, but something like this:

for(var i = 0; i < arrayName.length; i++) {
    if(arrayName[i].toLowerCase() === "whatever") {
        //Found a match!
    }
}

Post some more of your code and it will be easier to provide a more precise solution! Here's an example of the above.

answered Nov 9, 2011 at 22:43

James Allardice

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1 Comment

user1038065 Over a year ago

Hi, sorry for being so vague. I have posted some code above. Thank you

rkw · Accepted Answer · 2011-11-09 22:51:17Z

6

You can't use toLowerCase() on an array, unless you extend it.

Put this somewhere in your code, then from here on out, you can use it on arrays (note, only if your array is filled with strings)

Array.prototype.toLowerCase = function() { 
    for (var i = 0; i < this.length; i++) {
        this[i] = this[i].toString().toLowerCase(); 
    }
}

answered Nov 9, 2011 at 22:51

rkw

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Comments

Will · Accepted Answer · 2011-11-09 23:00:07Z

3

Arrays do not have a toLowerCase method. You can create one or just call toLowerCase on each string when iterating through the array.

Array.prototype.toLowerCase = function() {
    var i = this.length;
    while ( --i >= 0 ) {
        if ( typeof this[i] === "string" ) {
            this[i] = this[i].toLowerCase();
        }
    }
    return this;
};

For the code you posted, you can change var a = (array[i].indexOf(searchlow)); to

var a = (array[i].toLowerCase().indexOf(searchlow));

edited Nov 9, 2011 at 23:00

answered Nov 9, 2011 at 22:54

Will

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Comments

Sumit · Accepted Answer · 2018-10-17 11:04:24Z

3

Another way using ES6, with Array.prototype.map and arrow function.

var arr = ['Billie', 'Jean'];
var arr_lower = arr.map(item => item.toLowerCase());
console.log(arr_lower);

answered Oct 17, 2018 at 11:04

Sumit

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Comments

Amritpal Singh · Accepted Answer · 2011-11-09 22:43:16Z

2

you can not call toLowerCase on array object you need to call on individual member of array

answered Nov 9, 2011 at 22:43

Amritpal Singh

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Comments

Martie Henry · Accepted Answer · 2015-12-06 10:51:36Z

2

Personally, I find it much easier to do it this way:

                array = ["Apples","Oranges","FRUIT"];
                console.log("array: "+array); //array: Apples,Oranges,FRUIT
                arrayString = array.toString();
                arrayLowerString = arrayString.toLowerCase();
                arrayLower = arrayLowerString.split(",");
                console.log("arrayLower: "+arrayLower); //apples,oranges,fruit

answered Dec 6, 2015 at 10:51

Martie Henry

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1 Comment

Paul Kane Over a year ago

This works, or maybe you could simply concatenate all three methods into one? var arrayLowerString = array.toString().toLowerCase().split(',')

Reza Saadati · Accepted Answer · 2019-06-15 17:03:23Z

1

array_name_tolowercase = array_name.map(x=>x.toLowerCase)

edited Jun 15, 2019 at 17:03

Reza Saadati

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answered Feb 13, 2018 at 6:17

Quimby

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Comments

zero298 · Accepted Answer · 2015-12-29 23:58:12Z

0

function(resp) {
    return this.colors.filter(function(color) {
        return color.toLowerCase() === resp.toLowerCase();
    })[0];
}

edited Dec 29, 2015 at 23:58

zero298

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answered Dec 29, 2015 at 22:14

minki

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