UsefulJavascript

Index

• Find out from where a function is being called
• Get the stack trace for an error
• Invoke a Callback function
• Measure code execution time
• Set a default value for a JavaScript function parameter

Find out from where a function is being called

If we add this to a function, it will show a Stack Trace.

console.log( ( new Error() ).stack );

Get the stack trace for an error

try {
	...
}
catch( oEx ) {
	console.log( oEx.message )
	console.log( oEx.stack );
}

Invoke a Callback function

If we have a callback function:

var fCallback = function () {};

Instead of invoking the function directly:

fCallback();

We use the .call() function to pass the current object to the function, making it available inside the callback:

fCallback.call( this );

Measure code execution time

We can use the performance.now() function like this:

var t0 = performance.now();
// Some code here to measure its execution time
var t1 = performance.now();
console.log( 'Execution time was: ' + ( t1 - t0 ) + " ms" );

Set a default value for a JavaScript function parameter

In this example we want the default value for the sampleParamter to be false:

function sampleFunction( sampleParameter ) {
    sampleParameter = typeof sampleParameter !== 'undefined' ? sampleParameter : false;
}