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Hello , I am making a rock paper scissors game to exercise with javascript. But i don't get why this code doesn't work. if I activate function start then var begin is supposed to be true but when I, for example, activate function rock then it doesn't say rock in the console. Can someone help me?

By adding var in start function you're declaring another local variable start.

Replace start function with

function start(){
    begin = true;
    document.getElementById("player").id = "current";

Boolean operators in if statement not working, var foo = undefined;. foo will return true. Because, in JavaScript "", undefined, 0, NaN, false and null are considered falsey values. Due to the two boolean evaluations submitInput() is only called if the given input is a string that contains non-whitespace characters. In JavaScript && returns its first argument if it is falsy or its second argument if the first argument is truthy; so normalized will be undefined if someString was undefined and so forth. That means that none of the inputs to the boolean expressions above are actually boolean values.

With var begin inside of the start() function you declare a new local variable. If you set that to true the outer variable with the same name won't be affected. To set the outer one instead, don't declare the variable but just set it:

 begin = true;

Why this simple IF statement won't work?, The if statement doesn't work. Even if the element Why is the javascript loose equality not the same as the truthy test? javascript. asked by  Javascript if condition on boolean. Ask Question Can you explain why the if condition doesn't work without the eval function: Making statements based on

You only set begin to true within the scope of the start function. If you change the start code to begin = true it should work.

When you declared var begin inside your start function that variable was scoped to the function. And when you accessed begin in the other functions you were accessing the global begin which had never been changed from false

JavaScript Booleans, A JavaScript Boolean represents one of two values: true or false. You can use the Boolean() function to find out if an expression (or a variable) is true: When using the === operator, equal booleans are not equal, because the === operator​  If you work with other developers, they won't have to spend time and brainpower trying to figure out what your names mean. If you think you'll come back to this project after a while, you might as well be a different developer.

Add conditions - Learn to code with JavaScript, if (condition) { // Statements executed when the condition is true } Any expression producing a Boolean value (either true or false) can be used if (​condition) { // code to run when condition is true } else { // code to run when condition is not true } Introduction to programming · Understand JavaScript · Configure your work  If statements are another core part of JavaScript: they let you control what code is actually executed, based on comparing values and/or variables. I’ll also teach you about all the cool stuff that you can do with booleans!

ifelse, The if statement executes a statement if a specified condition is truthy. To see how this works, this is how it would look if the nesting were properly indented: Do not confuse the primitive Boolean values true and false with  Can be any statement, including further nested if statements. To execute multiple statements, use a block statement ({ }) to group those statements. To execute no statements, use an empty statement. statement2 Statement that is executed if condition is falsy and the else clause exists.

JavaScript - Boolean logic, I first discuss the basic theory, then introduce AND, OR and NOT in JavaScript. When you've understood all this you can work with Boolean logic in JavaScript. In JavaScript we have the following conditional statements: Use if to specify a block of code to be executed, if a specified condition is true. Use else to specify a block of code to be executed, if the same condition is false. Use else if to specify a new condition to test, if the first condition is false.

  • please add the code in text form to the question.
  • You are a victim of hoisting
  • Please include your code in your question (as a working snippet if possible) rather than an image of your code.
  • Remove the var keyword from var begin = true;
  • Glad you see the problem (the extraneous "var begin") :) In the future, please copy/paste your text (instead of a screen shot). Even better, consider using "code snippets". Please also read about Javascript hoisting and the ES6 keyword let