测试计算器的小数字符串

Question

I have an array called userInput that I am pushing my input to eventually perform an eval() calculation on.

I am adding the decimal function but need to test if a number already has a decimal in my array to avoid something like 3.00.00.00.

My current function

function addPeriod() {
    if((inputArray.length == 0) || inputArray[inputArray.length -1] == '.') {
        //do nothing
    } else {
        inputArray.push('.');
        console.log(inputArray);
        screenText.append('.');
    }
}

The way my current userInput array looks now during operation once I use userInput.join('') is something like 3 + 2.00 / 1 etc... I know I need to use a regex method but not sure of the pattern that would eliminate the unwanted decimal occurrence. Thanks for the help.

Answer 1

You could split the input string on a decimal and count the length. Any input with 1 or 0 decimals should have a length of 2 or less.

 var test = "3.0" // Valid, return true var test2 = ".3.0" // Invalid, return false var test3 = "30" // Valid, return true console.log(test.split('.').length <= 2) console.log(test2.split('.').length <= 2) console.log(test3.split('.').length <= 2) 

Edit: While I personally prefer the readability and feel of the Regex answer, splitting is significantly faster when searching a string for existence of a certain character.

Here you can see a split() vs regex() speed test:

 var i = 0; var split_start = new Date().getTime(); while (i < 30000) { "1234,453,123,324".split(",").length -1; i++; } var split_end = new Date().getTime(); var split_time = split_end - split_start; i= 0; var reg_start = new Date().getTime(); while (i < 30000) { ("1234,453,123,324".match(/,/g) || []).length; i++; } var reg_end = new Date().getTime(); var reg_time = reg_end - reg_start; alert ('Split Execution time: ' + split_time + "\\n" + 'RegExp Execution time: ' + reg_time + "\\n"); 

Answer 2

This is the regex to test multiple dots:

 var text = "3.0.0"; var text1 = "3.0.00.00"; var text2 = "3.0"; var text3 = ".3.0"; var text4 = "30"; console.log(/^\\d+(\\.\\d{0,2})?$/.test(text)); console.log(/^\\d+(\\.\\d{0,2})?$/.test(text1)); console.log(/^\\d+(\\.\\d{0,2})?$/.test(text2)); console.log(/^\\d+(\\.\\d{0,2})?$/.test(text3)); console.log(/^\\d+(\\.\\d{0,2})?$/.test(text4)); 

Hope, this may help you.