Introduction to the console.assert() function in JavaScript_javascript skills

In the development and maintenance process of JavaScript programs, Assert is a good feature used to ensure the correctness of the program. On browsers with debugging tools, this feature can be achieved by calling console.assert(). For example, in the following code, the console.assert() statement ensures that the score variable value length of the cat object is 3:

Copy code The code is as follows:

function cat(name, age, score){
This.name = name;
This.age = age;
This.score = score;
}
var c = new cat("miao", 2, [6,8,7]);
console.assert(c.score.length==3, "Assertion of score length failed");

In the console.assert() statement, the first parameter is the result that needs to be asserted, which should be true under normal circumstances; the second parameter is the error message printed on the console when an error occurs. For example, when the array length of the score variable in the above example is not 3:

Copy code The code is as follows:

function cat(name, age, score){
This.name = name;
This.age = age;
This.score = score;
}
var c = new cat("miao", 2, [6,8]);
console.assert(c.score.length==3, "Assertion of score length failed");

After the code is executed, the Firebug console will print the error message:

Browser support

console.assert() is better supported on browsers with debugging tools, and all major browsers support this function. However, it is worth mentioning that Firefox itself does not support this function. The Firebug plug-in must be installed on Firefox to use console.assert().