Essential Vanilla JavaScript Functions

Essential Vanilla JavaScript Functions

Some of the missing functions in JavaScript in vanilla form (inspired by PHP). You can just try it as a programming practice.

Array Functions

array_unique()

Remove duplicates from an array

function array_unique(arr){
    var seen = {};
    var ret_arr = [];
    var key;
    var i;

    function keyify(obj){
        var ret = "";
        var j;

        if (Object.prototype.toString.call(obj) === "[object Object]" || Object.prototype.toString.call(obj) === "[object Array]"){
            for (j in obj){
                ret += "~" + j + "^" + keyify(obj[j]) + "%";
            }
            return ret;
        }else{
          return obj;
        }
    }

    for(i = 0; i < arr.length; i++){
        key = keyify(arr[i]);
        if(!(key in seen)){
            ret_arr.push(arr[i]);
            seen[key] = true;
        }
    }

    return ret_arr;
}

array_unique([4,5,4,6,7,8,2,6]);
// [4, 5, 6, 7, 8, 2]
array_unique([{a: 'val'}, {b: 'val', c: 'val'}, 'a', 'b', [1,2,3,4], {a: 'val'}, [1,2,3,4], [{a: 'val'}, {b: 'val'}], [{a: 'val'}, {b: 'val'}]]);
// [{a: 'val'}, {b: 'val', c: 'val'}, 'a', 'b', [1,2,3,4], [{a: 'val'}, {b: 'val'}]]

array_merge()

Merge two arrays

function array_merge(arr1, arr2){
    for(var i=0; i<arr2.length; i++){
        arr1.push(arr2[i]);
    }

    return arr1;
}

array_merge([1, 2, 3], [4, 5]);
// [1, 2, 3, 4, 5]

array_chunk()

Splits an array into chunks of arrays

function array_chunk(arr, count){
    var temp_arr = [];

    for(var i=0; i<arr.length;){
        var chunk_arr = [];
        for(var j=0; j<count; j++){
            if(!arr[i])
                break;
            chunk_arr.push(arr[i]);
            i++;
        }
        temp_arr.push(chunk_arr);
    }

    return temp_arr;
}

array_chunk([1,2,3,4,5,6,7,8,9], 4);
// [ [ 1, 2, 3, 4 ], [ 5, 6, 7, 8 ], [ 9 ] ]

array_collapse()

Collapses a collection of arrays into a single, flat array

function array_collapse(...arrays){
    var collapse_arr = [];

    for(var i=0; i<arrays.length;i++){
        for(var j=0; j<arrays[i].length; j++){
            collapse_arr.push(arrays[i][j]);
        }
    }

    return collapse_arr;
}

array_collapse([1, 2, 3, 4], [5, 6], ["hello", "world"]);
// [ 1, 2, 3, 4, 5, 6, 'hello', 'world' ]

array_diff()

Returns the values in the arr1 that are not present in arr2

function array_diff(arr1, arr2){
    var temp_arr = [];

    for(var i=0; i<arr1.length; i++){
        if(arr2.indexOf(arr1[i]) == -1){  
            temp_arr.push(arr1[i]);
        }
    }

    return temp_arr;
}

array_diff([4,5,6,7, "unicorn"], [5, 6, 7]);
// [ 4, 'unicorn' ]

array_intersect()

Returns the values common in the two supplied arrays

function array_intersect(arr1, arr2){
    var temp_arr = [];

    for(var i=0; i<arr1.length; i++){
        if(arr2.indexOf(arr1[i]) != -1){  
            temp_arr.push(arr1[i]);
        }
    }

    return temp_arr;
}

array_intersect([4,5,6,7, "unicorn"], [5, 6, 7, 8]);
// [ 5, 6, 7 ]

array_map()

Sends each value of an array to a user-made function, which returns new values

function array_map(arr, func){
    var temp_arr = [];

    if(typeof func !== "function")
        throw "Second parameter should be a function";

    for(var i=0; i<arr.length; i++){
        temp_arr.push(func(arr[i]));
    }

    return temp_arr;
}

array_map([1, 2, 3, 4, 5], function (value) {
    return value * 2;
});
// [ 2, 4, 6, 8, 10 ]

array_reject()

Filters the array using the given callback. The callback should return true if the item should be removed from the resulting array

function array_reject(arr, func){
    var temp_arr = [];

    if(typeof func !== "function")
        throw "Second parameter should be a function";

    for(var i=0; i<arr.length; i++){
        if(func(arr[i]))
            temp_arr.push(arr[i]);
    }

    return temp_arr;
}

array_reject([1, 2, 3, 4, 5], function (value) {
    return value > 3;
});
// [ 4, 5 ]

array_split()

Breaks an array into the given number of groups

function array_split(arr, count){
    var temp_arr = [];
    var arr_length = arr.length;

    var chunk = Math.floor(arr_length/count);

    for(var i=0; i<arr.length;){
        var chunk_arr = [];

        if(temp_arr.length == (count-1))
            chunk = chunk + (arr_length-i);

        for(var j=0; j<chunk; j++){
            if(!arr[i])
                break;
            chunk_arr.push(arr[i]);
            i++;
        }

        temp_arr.push(chunk_arr);
    }

    return temp_arr;
}

array_split([1,2,3,4,5,6,7,8,9], 4);
// [ [ 1, 2 ], [ 3, 4 ], [ 5, 6 ], [ 7, 8, 9 ] ]

array_take()

Returns a new array with the specified number of items

function array_take(arr, count){
    var temp_arr = [];

    if(count<0){
        count = Math.abs(count);
        for(var i=(arr.length-count); i<arr.length; i++){
            temp_arr.push(arr[i]);
        }
    }else{
        for(var i=0; i<count; i++){
            temp_arr.push(arr[i]);
        }
    }

    return temp_arr;
}

array_take([1,2,3,4,5,6,7,8,9], 4);
// [ 1, 2, 3, 4 ]

You may also pass a negative integer to take the specified amount of items from the end of the array:

array_take([1,2,3,4,5,6,7,8,9], -3);
// [ 7, 8, 9 ]

array_pad()

Inserts a specified number of items, with a specified value, to an array

function array_pad(arr, size, value){
    for(var i=0; i<size; i++){
        arr.push(value);
    }
    return arr;
}

array_pad([1,2,3,4], 2, "unicorn");
// [ 1, 2, 3, 4, 'unicorn', 'unicorn' ]

range()

Creates an array containing a range of elements

function range(start, end){
    var temp_arr = [];

    for(var i=start; i<=end; i++){
        temp_arr.push(i);
    }

    return temp_arr;
}

range(5, 11);
// [ 5, 6, 7, 8, 9, 10, 11 ]

String Functions

chunk_split()

Splits a string into a series of smaller parts

function chunk_split(string, length, end){
    var temp_string = '';

    for(var i=0; i<string.length; i++){
        temp_string += string[i];
        if((i+1)%length==0)
            temp_string += end;
    }

    return temp_string;
}

console.log(chunk_split("Hello", 1 , "."));
// H.e.l.l.o.
console.log(chunk_split("Hello", 1 , ".."));
// H..e..l..l..o..

str_pad()

Pads a string to a new length

function str_pad(string, size, value){
    for(var i=0; i<size; i++){
        string += value;
    }

    return string;
}

str_pad("unicorn", 5 , ".");
// unicorn.....

strrev()

Reverses a string

function strrev(string){
    var temp_string = '';

    for(var i=string.length-1; i>=0; i--){
        temp_string += string[i];
    }

    return temp_string;
}

strrev("unicorn");
// nrocinu

similar_text()

Calculates the similarity between two strings

function similar_text(string1, string2){
    var seen = {};
    var similar_count = 0;

    for(var i=0; i<string1.length; i++){
        if((string2.indexOf(string1[i]) !== -1 && !(string1[i] in seen)) 
                || string1[i]==' ')
        {
            similar_count++;
            if(string1[i]!='')
                seen[string1[i]] = true;
        }
    }

    return similar_count;
}

similar_text("Hello World","Hello Peter");
// 6

Originally published at amitmerchant1990/essential-vanilla-javascript-functions.

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