Master JavaScript Debugging: Console Tricks to Trace, Table, and Profile Code

Trace Stack

Use console.trace() to track the call stack and see exactly where a function was invoked.

function func_A() {
    func_B(1, 2);
}
function func_B(arg1, arg2) {
    console.trace();
}
func_A();

Display Object Information as Table

Printing objects with console.log() can be hard to read; console.table() formats them as a readable table.

var books = [
    { title: "Java", author: "Abc" },
    { title: "C", author: "Obj" },
    { title: "C++", author: "Cof" }
];
console.log(books);

Result shown in the image below.

Using console.table() improves readability.

console.table(books);

Measure Execution Time

Use console.time() and console.timeEnd() to measure how long a block of code runs.

console.time('timer');
for (var i = 0; i < 100000; i++) {
    // ...
}
console.timeEnd('timer');

Profile CPU Consumption

console.profile()

and console.profileEnd() let you see CPU usage and identify time‑consuming code.

function func_A(num){
    for(var i=0;i<num;i++){
        console.log('A');
    }
}
function func_B(x,y){
    for(var i=0;i<x;i++){
        for(var j=0;j<y;j++){
            console.log('B');
        }
    }
}
function test(){
    func_A(100);
    func_B(3,10);
}
console.profile('test');
test();
console.profileEnd();

The profiling result shows each function’s self time (time spent in the function itself) and total time (including time spent in called functions).