Nightwatch.js cannot set a string variable to an input field?

问题

I am testing some JavaScript code with Nightwatch.js. I want to read a value from an input tag, increase or decrease it by 1 and then write it back to the input tag. Therefore I wrote this code:

.getValue('#inputConfigReading', function(result){
    val = parseInt(result.value);
    if (val % 2 == 0)
        val++;
    else
        val--;
    val = val+'';
})
.clearValue('#inputConfigReading')
.setValue('#inputConfigReading', val)

I checked it out. The variable val has the correct value after the command val = val+'';. But anyway when I run the code Nightwatch is writing undefined into the input field. Why?

回答1:

Nightwatch is executing those last two steps before val is defined. Those last two steps should be inside the callback function of .getValue:

.getValue('#inputConfigReading', function(result){
    val = parseInt(result.value);
    if (val % 2 == 0)
        val++;
    else
        val--;
    val = val+'';
    browser.clearValue('#inputConfigReading')
    browser.setValue('#inputConfigReading', val)
})

来源：https://stackoverflow.com/questions/31240656/nightwatch-js-cannot-set-a-string-variable-to-an-input-field