Calculate how long it takes to perform a function

Question

Calculate how long it takes to perform a function

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#1 by (7 votes)
#2 by (7 votes)

5

I have to create a function in JavaScript that takes all the id's from a table and makes a draw with id's of the same table so that a same id does not fall with itself, and that there is a possibility that this id can being in the other "home".

exps:

1|2 - 2|1... válido.
1|1 - 2|2... inválido.

In this way:

var teste = [];

for (var i = 1; i <= 305; i++) {
	for (var x = 1; x <= 305; x++) {
        if(x != i){
            teste.push(i+'|'+x);
        }
    }
}
console.log(teste)

I would like to know if there is any way to know how long this function takes to run, since it generates more than 90,000 records.

javascript desempenho

asked by anonymous 26.03.2015 / 14:56

2 answers

7

To measure runtime you can use performance.now () , example:

var teste = [];
var inicio = performance.now();
for (var i = 1; i <= 305; i++) {
	for (var x = 1; x <= 305; x++) {
        if(x != i){
           teste.push(i+'|'+x);
        }
    }
}
   
var fim = performance.now();
console.log(teste)
alert('Tempo de excução: ' + (fim - inicio));

Another option is console.time ()

console.time () strong> example:

var teste = [];
console.time('tempo');
for (var i = 1; i <= 305; i++) {
	for (var x = 1; x <= 305; x++) {
        if(x != i){
            teste.push(i+'|'+x);
        }
    }
}
console.timeEnd('tempo');
console.log(teste)

26.03.2015 / 15:09

Select with undefined number of conditions Analysis of the machine / server using php

score 7 · Accepted Answer

To measure the runtime, with resolution of milliseconds, just compare the timestamp before after execution:

function fn() {
    var teste = [];
    
    for (var i = 1; i <= 305; i++) {
    	for (var x = 1; x <= 305; x++) {
            if(x != i){
                teste.push(i+'|'+x);
            }
        }
    }
}
var antes = Date.now();
fn();
var duracao = Date.now() - antes;
document.body.innerHTML = "levou " + duracao + "ms";

If your browser does not support Date.now() ( for example, IE8 or earlier), just use new Date().getTime() .

As for estimating the time it would take, before running, there I no longer know the answer. What you can estimate is the level of complexity, but the execution time will depend on several factors, I do not know if it is possible.