[].push() – add an item at a very end of the array :

let add_at_the_end = [1, 2, 3, 4, 5];
add_at_the_end[add_at_the_end.length] = 6;
console.log(add_at_the_end); // [1, 2, 3, 4, 5, 6]

[].unshift() – add an item at the beginning of the array :

let add_at_the_beginning = ["added at the beginning", ...[1, 2, 3, 4, 5]];
// instead of ...*spread*, we could use ["added at the beginning"].concat([1, 2, 3, 4, 5]); 
console.log(add_at_the_beginning); // ["added at the beginning", 1, 2, 3, 4, 5]

[].pop() – remove an item at the end of the array :

let remove_at_the_end = [1, 2, 3, 4, 5];
remove_at_the_end.length = remove_at_the_end.length-1;
console.log(remove_at_the_end); // [1, 2, 3, 4]

[].shift() – remove an item at the beginning of the array :

let remove_at_the_end = [1, 2, 3, 4, 5];
remove_at_the_end.reverse.call(remove_at_the_end).length = remove_at_the_end.length-1;
console.log( remove_at_the_end.reverse.call(remove_at_the_end) ); // [2, 3, 4, 5]

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Math.min() / Math.max() from array as [native code] :

let array = [300, 15, -20, 0, -101, 404];
let min = array[0]; // set it to zero so every indexed value of m would be read
let max = array[0]; // set it to zero so every indexed value of m would be read

for (let i = 0; i < array.length; i++) {
    if (array[i] > max) {
        max = array[i];
    }
    if (array[i] < min) {
        min = array[i];
    }
}

console.log("min of the array: ", min, "max of the array: ", max);

Math.min() / Math.max() from array with .apply() :

let array = [300, 15, -20, 0, -101, 404];
let 
min = Math.min.apply(null, array), /* null could be this but Math.min() do not consume this internally */
max = Math.max.apply(null, array); /* null could be this but Math.max() do not consume this internally */

console.log("min of the array: ", min, "max of the array: ", max);

Math.min() / Math.max() from array instead of .apply() use ...spread operator (ES6) :

let array  = [300, 15, -20, 0, -101, 404];
let 
min = Math.min(...array),
max = Math.max(...array);

console.log("min of the array: ", min, "max of the array: ", max);