What is the statement in javascript to implement function return value?

In JavaScript, the statement that implements function return value is return, and the syntax is "return [return value];". In the function body, you can use the return statement to set the return value of the function; once the return statement is executed, the function will stop running, and the value of the expression following the return will be calculated and returned.

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

The JavaScript function provides two interfaces to interact with the outside world. The parameters serve as the entrance to receive external information; the return value serves as the outlet to feed back the operation results to the outside world.

In the function body, use the return statement to set the return value of the function. Once the return statement is executed, the execution of the function will stop, and the value of the expression following the return will be evaluated and returned. If the function does not contain a return statement, an undefined value will be returned after each statement in the function body is executed.

JavaScript is a weakly typed language, so functions have no type restrictions on the values ​​they receive and output, and JavaScript does not automatically detect the types of input and output values.

Example 1

The following code defines the return value of the function as a function.

function f() {
    return function(x,y) {
        return x + y;
    }
}

Example 2

The parameters of the function are not limited, but the return value can only be one; if you want to output multiple values, you can design it through an array or object.

function f() {
    var a = [];
    a[0] = true;
    a[1] = function(x,y) {
        return x + y;
    }
    a[2] = 123;
    return a;  //返回多个值
}

In the above code, the function return value is an array, which contains 3 elements, thus achieving the purpose of using one return statement to return multiple values.

Example 3

The function body can contain multiple return statements, but only one return statement can be executed. Therefore, the branch structure can be used in the function body to determine the function return value. , or use the return statement to terminate function execution early.

function f(x,y) {
    //如果参数为非数字类型，则终止函数执行
    if (typeof x != "number" || typeof y != "number") return;
    //根据条件返回值
    if (x > y) return x - y;
    if (x < y) return y - x;
    if (x * y <= 0) return x + y;
}

[Recommended learning: javascript advanced tutorial]

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