JavaScript functions' implementation inspired by PHP and Laravel

Amit Merchant · March 29, 2019

A sometime ago I tried my hands on implementing some of the PHP’s native functions in native JavaScript. The result is quite interesting list of JavaScript functions you’ve never asked about.

Here some of the function implementation are also inspired from Laravel Collections functions. Let’s go.

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 ]

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.

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

In closing

I’m in no way claiming these functions to be efficient then the existing correponding native JavaScript functions. I just tried to challenge myself if I can write my own implementation or not and it was a fun little exercise. I hope you learned a thing or two just like I learned while implementing them.

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