How to convert a Z Score to a P Value?

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//the following function originated from https://stackoverflow.com/questions/16194730/seeking-a-statistical-javascript-function-to-return-p-value-from-a-z-score/30435852

function GetZPercent()
{
var z_input = document.getElementById(‘z’).value*1;
var z = Math.abs(z_input);

//if z is greater than 6.5 standard deviations from the mean
//the number of significant digits will be outside of a reasonable
//range
if ( z 6.5)
return 1.0;

var factK = 1;
var sum = 0;
var term = 1;
var k = 0;
var loopStop = Math.exp(-23);
while(Math.abs(term) > loopStop)
{
term = .3989422804 * Math.pow(-1,k) * Math.pow(z,k) / (2 * k + 1) / Math.pow(2,k) * Math.pow(z,k+1) / factK;
sum += term;
k++;
factK *= k;

}
sum += 0.5;

var p_value = 1 – sum;

//get tails input
if (document.getElementById(‘two_tailed’).checked) {
p_value = p_value * 2;
}

//get significance level input
var sig_level = ”;
if (document.getElementById(‘one’).checked) {
sig_level = 0.01;
} else if (document.getElementById(‘five’).checked) {
sig_level = 0.05;
} else {
sig_level = 0.10;
}

//get significance verdict
var sig_verdict = ”;
if (p_value < sig_level) {
sig_verdict = 'SIGNIFICANT';
} else {
sig_verdict = 'NOT SIGNIFICANT';
}

//output values
document.getElementById('exactProb').innerHTML = p_value.toFixed(5);
document.getElementById('sig_level').innerHTML = sig_level.toFixed(2);
document.getElementById('sig_verdict').innerHTML = sig_verdict;
}