How to use the arithmetic function in JavaScript tips

javascript| Function | technique | operation

This is a special built-in function eval includes an operand for its arguments, an operand, and a value to be returned. This function is useful for computing a numeric string that is represented, for example, the value entered from form is always a string, but you may want to do it, so what should I do?

The following example packages the input text field, applies the Operation function, and displays the result of another block. If you hit a numeric expression in the first field, and the button is pressed, the expression is opened to the operation,

function Compute (obj) {
Obj.result.value = eval (obj.expr.value)
}

Enter An expression:
Result: >

The following is the original syntax

In this example we have built two buttons, and the two presses will call Statbar (TXT). The TXT in the function indicates that this function will pass a variable value through the function call (we call txt but it can represent any number of different values) you can see in the

Write directly to the text to be displayed on the Status column, so we can see the effect that the variable txt passes through the value in ' value ' and then into the function called. So when you press the "Show" button, the Statbar (TXT) function is called, and txt reads the string "Hi this is the Status column message" and in the function, the way in which the value is passed through the variable, the function can be quite denatured.

Then look at the second button "clear" It also calls the same function, and we don't need two different functions to pass the argument differently. So now we can look at what the Statbar (TXT) function does, but it's quite simple. All you have to do is to assign the text content of txt to window.status this variable. That is Window.status =txt, and when the State column is cleared, only the empty string is written. Note, however, that it is easy to distinguish between single and double quotes.