use strict

Strict Mode

예제코드

'user strict'
function testFunction() {
	var testvar = 4;
	return testvar;
}
// This causes a stntax error.
testvar = 5;
function testFunction() {
	'use strict'
	// This causes a syntax error.
	testvar = 4;
	return testvar;
}
testvar = 5;