ReferenceError: Invalid left-hand side in assignment

javascript logic
Kevin picture Kevin · Sep 3, 2013 · Viewed 156.5k times · Source

my code for a rock paper scissors game (called toss) is as follows:

var toss = function (one,two) {
    if(one = "rock" && two = "rock") {
        console.log("Tie! Try again!");
    }
    // more similar conditions with `else if`
};

When I enter in the parameters

toss("rock","rock")

I get this error code:

"ReferenceError: Invalid left-hand side in assignment"

How to fix it? What this error means and what other cases when this error can happen?

Answer

Joseph Silber picture Joseph Silber · Sep 3, 2013

You have to use == to compare (or even ===, if you want to compare types). A single = is for assignment.

if (one == 'rock' && two == 'rock') {
    console.log('Tie! Try again!');
}

Related questions

JQuery .hasClass for multiple values in an if statement

I have a simple if statement as such: if ($('html').hasClass('m320')) { // do stuff } This works as expected. However, I want to add more classes to the if statement to check if any of the classes are present in …

Read More
jQuery password strength checker

I'm quite new to jQuery, and I've written a simple function to check the strength of a password for each keypress. The idea is that every time a user enters a character, the contents is evaluated to test the strengh …

Read More
Which Logic Operator Takes Precedence

So, I'm looking into writing a slightly more complex operation with logic operators in an if-else statement. I know I can do parentheses, and I know it's the better way of doing this, but I've gotten curious and so I'm …

Read More