Skip to main content


Showing posts from July, 2017

Let it be...

Definition : The let statement declares a block scope local variable, optionally initializing it to a value. What different between var and let ? It is mathematical statement.Remember in Math class, our teacher always mention let , for example: If we let A be the statement "You are rich" and B be the statement "You are happy", then the negation of "A or B" becomes "Not A and Not B." The question already answered in : Why was the name 'let' chosen for block-scoped variable declarations in JavaScript? The different , notice the code below is using var, once you define same variable in local scope in second time , it will overwrite  the variable in global scope, function varTest() { var x = 1 ; if ( true ) { var x = 2 ; // same variable! console.log(x); // 2 } console.log(x); // 2 } Using let, help to identify which belong to which. function letTest() { let x = 1 ; if ( true ) {