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This article mainly shows you "how to use JavaScript! operator to convert Boolean value", the content is easy to understand, clear, hope to help you solve your doubts, the following let the editor lead you to study and learn "how to use JavaScript! operator convert Boolean value" this article.

Use! Operator to convert Boolean values

Sometimes we need to check for the existence of a variable or check whether the value has a valid value, and return the true value if it exists. In order to do such a verification, we can use! Operator to implement is very convenient and simple. For variables, you can use! variable to detect, as long as the value of the variable is: 0, null, "", undefined, or NaN will return false, and vice versa. For example, the following example:

Function Account (cash) {this.cash = cash; this.hasMoney =!! cash;} var account = new Account (100.50); console.log (account.cash); / / 100.50 console.log (account.hasMoney); / / true var emptyAccount = new Account (0); console.log (emptyAccount.cash); / / 0 console.log (emptyAccount.hasMoney); / / false

In this example, as long as the value of account.cash is greater than 0, the value returned by account.hasMoney is true.

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