GoogleFeud / ts-zero-cost-iters

A typescript plugin which transpiles multiple array methods like map, filter, reduce, etc. into a single for loop.

ts-zero-cost-iters

ts-zero-cost-iters is a typescript plugin which combines array functions like filter, map and reduce into a single for loop. Example:

const array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const result = array.filter(num => num % 2 === 0).map(num => num * 2).join("+");

to:

const array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
var arrLen_1 = array.length, arrItem_1, i_1 = 0;
var result = "";
for (; i_1 < arrLen_1; i_1++) {
    arrItem_1 = array[i_1];
    if (!(arrItem_1 % 2 === 0))
        continue;
    result += arrItem_1 * 2 + (i_1 === arrLen_1 - 1 ? "" : "+");
}

Install

You need the ttypescript package in order to use this: npm i ttypescript

After that put this in your tsconfig.json:

"compilerOptions": {
//... other options
"plugins": [
        { "transform": "ts-macros" }
]
}

And run your code with ttsc

ts-zero-cost-iters in-depth

.length

If the chain ends with a .length, then the generated output will NEVER create a new array, it's just going to count the elements.

const result = array.filter(num => num % 2 === 0).length;

var arrLen_1 = array.length, arrItem_1, i_1 = 0;
var result = 0;
for (; i_1 < arrLen_1; i_1++) {
    arrItem_1 = array[i_1];
    if (!(arrItem_1 % 2 === 0))
        continue;
    result++;
}