80 lines
2.1 KiB
Markdown
80 lines
2.1 KiB
Markdown
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---
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id: 587d7b85367417b2b2512b38
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title: Catch Use of Assignment Operator Instead of Equality Operator
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challengeType: 1
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forumTopicId: 301191
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dashedName: catch-use-of-assignment-operator-instead-of-equality-operator
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---
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# --description--
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Branching programs, i.e. ones that do different things if certain conditions are met, rely on `if`, `else if`, and `else` statements in JavaScript. The condition sometimes takes the form of testing whether a result is equal to a value.
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This logic is spoken (in English, at least) as "if x equals y, then ..." which can literally translate into code using the `=`, or assignment operator. This leads to unexpected control flow in your program.
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As covered in previous challenges, the assignment operator (`=`) in JavaScript assigns a value to a variable name. And the `==` and `===` operators check for equality (the triple `===` tests for strict equality, meaning both value and type are the same).
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The code below assigns `x` to be 2, which evaluates as `true`. Almost every value on its own in JavaScript evaluates to `true`, except what are known as the "falsy" values: `false`, `0`, `""` (an empty string), `NaN`, `undefined`, and `null`.
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```js
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let x = 1;
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let y = 2;
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if (x = y) {
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// this code block will run for any value of y (unless y were originally set as a falsy)
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} else {
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// this code block is what should run (but won't) in this example
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}
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```
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# --instructions--
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Fix the condition so the program runs the right branch, and the appropriate value is assigned to `result`.
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# --hints--
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Your code should fix the condition so it checks for equality, instead of using assignment.
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```js
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assert(result == 'Not equal!');
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```
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The condition should use either `==` or `===` to test for equality.
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```js
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assert(code.match(/x\s*?===?\s*?y/g));
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```
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# --seed--
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## --seed-contents--
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```js
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let x = 7;
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let y = 9;
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let result = "to come";
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if(x = y) {
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result = "Equal!";
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} else {
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result = "Not equal!";
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}
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console.log(result);
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```
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# --solutions--
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```js
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let x = 7;
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let y = 9;
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let result = "to come";
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if(x === y) {
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result = "Equal!";
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} else {
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result = "Not equal!";
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}
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console.log(result);
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```
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